More than 80 per cent of the specimens from Michoacan have brown spots between the lateral and dorsolateral dark stripes, and more than 50 per cent have spots between the dorsolateral stripes, at least posteriorly.

In comparison with specimens from the Valley of Mexico, those from Michoacan have more distinct dorsolateral stripes that extend farther anteriorly, sometimes to the eyelid, and in this respect are more nearly like those from Jalisco and Nayarit (Taylor, 1939b:425). Some specimens from the western part of Michoacan possess certain characters used by Maslin (1957:81) to distinguish _Hyla microeximia_ from _H. eximia_; nevertheless, the variation is such that two species cannot be distinguished in Michoacan. Four series of freshly preserved specimens have been studied in detail; in the discussion below they are arranged from west to east; the measurement is for snout-vent length of ten males from each sample:

_Zamora._--Twenty-two specimens (UMMZ 102083), 24.0-27.6 (26.1) mm. Dorsolateral dark stripe, or row of dashes, present in all specimens; dark spots in lateral and dorsal green fields; lateral dark stripe confluent with dorsolateral stripe posteriorly in 18 specimens; white line not extending to groin.

_Temazcal._--Thirty-five specimens (UMMZ 119162), 26.5-31.1 (28.2) mm. Dorsolateral dark stripe of row of spots present only posteriorly in most; both dorsolateral stripes and dorsal spots lacking in four specimens; heavy spotting dorsally in three others; lateral and dorsolateral dark stripes confluent posteriorly in three; lateral white stripe extending to groin in 16 specimens.

_Ciudad Hidalgo._--Thirty-six specimens (UMMZ 119163), 26.4-30.9 (28.2) mm. Dorsolateral dark stripe or row of spots present only posteriorly in most; no brown spots in the green fields of many specimens; large brown inguinal spot in most specimens; heavy spotting dorsally in four; lateral and dorsolateral dark stripes confluent posteriorly in five; lateral white line extending to groin in most specimens.

_Tuxpan._--Fifteen specimens (UMMZ 115227), 28.7-33.0 (30.5) mm. Dorsolateral dark stripe or row of dashes in all specimens; dark spots in lateral green fields, at least posteriorly in most; dark spots posteriorly in the dorsal green field in five; lateral dark stripe separated from dorsolateral stripe in all specimens; lateral white line extends to the groin in all specimens.

As can be seen from the above descriptions, the distinguishing characters of _Hyla microeximia_--confluence of lateral and dorsolateral dark stripes posteriorly, extent of lateral white stripe, and distribution of dark spots dorsally--are found in individuals from all of the populations sampled. In the samples from western Michoacan there is a higher incidence of _microeximia_-like frogs than in those from other parts of the state. _Hyla eximia_ is a wide-ranging species varying greatly geographically and individually. A thorough review of the species and related members of the _Hyla eximia_-group is necessary before certain populations can justifiably be segregated as subspecies or species.

In Michoacan _Hyla eximia_ has been collected in mesquite-gra.s.sland, pine-oak forest, and cultivated areas on the Mexican Plateau from 1500 to 2300 meters; apparently it is absent from the Sierra de Coalcoman.

This is the most abundant frog on the southern part of the Mexican Plateau; in the rainy season breeding choruses are found in temporary pools and in the marshes adjacent to the permanent lakes.

~Hyla lafrentzi~ Mertens and Wolterstorff

_Hyla lafrentzi_ Mertens and Wolterstorff, Zool. Anz., 84:235, August 25, 1929.--Desierto de los Leones, Distrito Federal, Mexico.

Cerro San Andres (26); Opopeo (9).

In March, 1949, James A. Peters collected this species at elevations of 2400 to 2800 meters on the west slope of Cerro San Andres. The frogs were found beneath logs and rocks in a damp canyon in coniferous forest.

Among the juveniles in this series is a completely transformed individual (UMMZ 102093) having a snout-vent length of 14.5 mm. Five adults have snout-vent lengths of 36.2-39.5 (38.0) mm. _Hyla lafrentzi_ has noticeably longer hind limbs than _H. eximia_; in the former, when the hind limb is brought forward along the body, the tibiotarsal articulation extends to the snout. There are dark transverse bands on the hind limbs; the dorsolateral stripe is broken into an anterior and a posterior segment, and the latter is narrowly bordered by white in most specimens.

_Hyla lafrentzi_ occurs at higher elevations than any other frog in Michoacan; the locality records from throughout the range indicate that it is restricted to pine and pine-fir forests. In these habitats it replaces _Hyla eximia_, which inhabits the lower pine-oak forests and mesquite-gra.s.sland on the Mexican Plateau. Ponds are absent at places where _Hyla lafrentzi_ has been collected; possibly the eggs are laid in streams.

~Hyla smaragdina~ Taylor

_Hyla smaragdina_ Taylor, Copeia, No. 1:18, March 30, 1940.--6 kilometers east of Cojumatlan, Michoacan, Mexico.

_Hylella azteca_ Taylor, Proc. Biol. Soc. Washington, 56:49, June 16, 1943.--Tepoztlan, Morelos, Mexico.

Cojumatlan (30); Copuyo (7); 18 km. E of Dos Aguas (22); Ostula (8); Pomaro (3); Sahuayo; Salitre de Estopilas (7).

Taylor (1940a:18) diagnosed this species as having few or no vomerine teeth, no vocal sac, a rather broad and flat head, two large tubercles below the a.n.u.s, a granular venter, and a green dorsum in life. The specimens on which the description was based are either immature or non-breeding individuals; all were collected from bromeliads growing on cacti near Cojumatlan. Another small, flat-headed hylid from Tepoztlan, Morelos, was described and diagnosed by Taylor (1943b:49) as differing from _Hyla smaragdina_ in having a vocal sac and a broader head. This specimen was named _Hylella azteca_. Specimens from the coastal region of Michoacan and Colima were referred to _Hylella azteca_ by Peters (1954:7) and Duellman (1958c:8).

Comparison of topotypic _Hyla smaragdina_ and the holotype of _Hylella azteca_ (UIMNH 25044) with the several series of specimens from Michoacan has resulted in the conclusion that all pertain to only one species. Although the type series of _Hyla smaragdina_ consists of immature specimens, the males in that series do possess vocal sacs.

Since these were not breeding individuals, the sacs are not well developed. The characters of the a.n.a.l tubercles and the relative width of the head are of no value in separating the two species. The apparently aestivating individuals comprising the type series of _Hyla smaragdina_, and the type of _Hylella azteca_, which also was found in a bromeliad, were green in life. Of the calling males found on the coast of Michoacan, most were yellowish tan when found; two were pale green, but soon changed to pale tan. Calling males from Copuyo and Dos Aguas were pale yellowish tan. Therefore the color of the dorsum is of little significance in distinguishing the two named populations.

Males of _Hyla smaragdina_ have been found calling in the months of June and July from rocky streams; the call is a nasal "haah-haah-haah,"

repeated quickly and constantly for as long as 30 seconds. As pointed out by Duellman (1958c:9), this breeding behavior is unlike that suggested by Taylor (1943b:51). In Michoacan _Hyla smaragdina_ has been found in tropical semi-deciduous forest, oak forest, and mesquite-gra.s.sland at elevations from 150 to 1500 meters.

~Hyla smithi~ Boulenger

_Hyla smithi_ Boulenger, Zool. Rec. Reptilia and Batrachia, 38:33, 1902.--Cuernavaca, Morelos, Mexico.

Aguililla (14); Apatzingan (104); Arteaga; Charapendo (5); Coalcoman (11); El Sabino (44); La Playa (6); Lombardia (2); Nueva Italia (8); Playa Azul; Salitre de Estopilas (2).

This small hylid is abundant in the Tepalcatepec Valley to elevations of about 1000 meters; it was found infrequently on the coastal lowlands.

Males call from bushes in and around flooded fields and ditches, from gra.s.ses and small herbs in the water and from vegetation overhanging small streams. The call consists of a series of short, high notes, somewhat reminiscent of a katydid's song. In the dry season occasional males were heard calling from irrigated fields near Apatzingan. In the daytime individuals were found in the axils of leaves of the elephant-ear plants (_Xanthosoma_).

In living individuals the dorsal color usually is uniform pale yellow; often the lateral white stripe is barely visible. The vocal sac is bright yellow, and the iris is pale gold. In some individuals there are scattered dark brown spots or flecks on the back and upper surfaces of limbs. Twenty males from Apatzingan have the following measurements: snout-vent length, 22.8-26.0 (25.0) mm., tibia length, 10.7-13.6 (12.6) mm.; head width, 7.2-8.0 (7.6) mm., head length, 7.1-8.1 (7.7) mm.

~Hypopachus caprimimus~ Taylor

_Hypopachus caprimimus_ Taylor, Univ. Kansas Sci. Bull., 26:526, November 27, 1940.--Agua del Obispo, Guerrero, Mexico.

Buena Vista; Copuyo (6); Charapendo (3); Cofradia; Jaramillo; Jungapeo; San Salvador; Tuxpan.

Specimens of _Hypopachus_ from the Balsas drainage in Michoacan have characters consistent with topotypic _H. caprimimus_. Eleven specimens from the southern edge of the Mexican Plateau all have the flanks darker than the dorsum, a distinct and continuous dark stripe from the occiput to the groin, a large dark spot in the inguinal region, and a pair of dark transverse stripes on the thigh and shank (Pl. 6, Fig. 1). With the exception of three specimens from Charapendo, all have a predominantly brown venter with round, cream-colored spots.

Peters (1954:8) referred specimens from Buena Vista and San Salvador to _Hypopachus oxyrrhinus_. He stated that the specimen (BMNH 1914.1.28.150) from San Salvador had flanks much darker than the dorsum and a well-defined continuous stripe from the occiput to the groin; this specimen has the characters of _H. caprimimus_. The specimen (BMNH 1914.1.28.151) from Buena Vista resembles _H. oxyrrhinus_ in some characters, but it is not like _H. oxyrrhinus ovis_ on the Mexican Plateau in Michoacan. The specimen has paired transverse stripes on the hind limbs as does _H. caprimimus_, and is here referred to that species.

In Michoacan this species has been collected in arid tropical scrub forest at elevations of 200 to 1800 meters in the northern foothills of the Sierra de Coalcoman, the Tepalcatepec and Tuxpan valleys, and on the lower slopes of the Cordillera Volcanica. Calling males have been found along streams. One specimen from Charapendo was regurgitated by a _Leptodeira maculata_.

~Hypopachus oxyrrhinus ovis~ Taylor

_Hypopachus ovis_ Taylor, Univ. Kansas Sci. Bull., 26:520, November 27, 1940.--Tepic, Nayarit, Mexico.

_Hypopachus oxyrrhinus ovis_, Shannon and Humphrey, Herpetologica, 14:89, July 23, 1958.

Emiliano Zapata; 30 km. NW of Jacona (2); 10 km. NE of Patzcuaro (2); Tangamandapio (16); 24 km. W of Zamora (16).

Thirty-seven specimens from the Mexican Plateau in northwestern Michoacan agree well with the diagnosis of _Hypopachus oxyrrhinus ovis_ by Shannon and Humphrey (1958). With the exception of one specimen from Tangamandapio, all have dark bellies extensively mottled or spotted with cream-color. Most of the specimens have some form of an irregular, usually broken, dark line from the occiput to the groin. In eight specimens there is no line or linear arrangement of spots; instead the dorsum is spotted or flecked with dark brown. The ground color of the dorsum and flanks varies from dull reddish brown to grayish brown; cream-colored spots are evident on the flanks and posterior surfaces of the thighs in all specimens (Pl. 6, Fig. 2).

In comparison with 14 specimens from Queseria, Colima (UMMZ 80001-2), individuals from the Mexican Plateau have a darker venter with bolder markings, and a more mottled dorsum.

In Michoacan this species has been taken between 1500 and 2200 meters on the Mexican Plateau, where it inhabits mesquite-gra.s.sland and cultivated areas.

~Rana dunni~ Zweifel

_Rana dunni_ Zweifel, Copeia, no. 2:78, July 15, 1957.--Lago de Patzcuaro, Michoacan, Mexico.

Lago de Patzcuaro (23); Rio de Morelia, near Undameo (8).

Aside from the type series of this species, there are in the Museum of Zoology at the University of Michigan six specimens taken from "tanks"

at the limnological station at Patzcuaro by Paul S. Martin in 1948, and eight specimens found in shaded ditches along the Rio de Morelia by Robert R. Miller on April 4, 1957. The Rio de Morelia flows into Lago de Cuitzeo; this drainage is separated from Lago de Patzcuaro by a chain of hills about 2400 meters in elevation. Dr. Richard G. Zweifel has examined these specimens and has informed me that, although they differ slightly from typical _Rana dunni_, they are much closer to that species than to _Rana montezumae_.

~Rana megapoda~ Taylor

_Rana megapoda_ Taylor, Univ. Kansas Sci. Bull., 28:310, November 12, 1942.--Chapala, Jalisco, Mexico.