1783. Allgemeine Naturgeschichte der Schildkroten, nebst einem system. Verzeichnisse der einzelnen arten. Leipzig, "2 Kpftaf. (wovon 1 illum.) gr. 8" (from Engelmann, W., 1846, Bibliotheca Historico-naturalis. 1700-1846, p. 422).

SCHOEPFF, I. D.

1795. The Historia Testudinum iconibus ill.u.s.trata. Fasc. 5.

Erlangen, Plag. L-O (32 pp.), 6 pls.

SCHWARTZ, A.

1956. The relationships and nomenclature of the soft-sh.e.l.led turtles (genus _Trionyx_) of the southeastern United States.

Charleston Mus. Leaflet, 26:1-21, 1 fig., 2 maps, 3 pls., May.

* SCHWEIGGER, A. F.

1812. Monographiae cheloniorum. Konigsberger Arch. Naturwiss.

Math., 1:271-368, 406-458 (from Loveridge and Williams, 1957:533).

SHIELDS, L. M., and LINDEBORG, R. G.

1956. Records of the spineless soft-sh.e.l.led turtle and the snapping turtle from New Mexico. Copeia, 1956(2):120-21, May 29.

SHOCKLEY, C. H.

1949. Fish and invertebrate populations of an Indiana ba.s.s stream.

Invest. Indiana Lakes Streams, 3(5):247-70, 4 figs., 4 tables.

SHOUP, C. S., PEYTON, J. H., and GENTRY, G.

1941. A limited biological survey of the Obey River and adjacent streams in Tennessee. Jour. Tennessee Acad. Sci., 16(1):48-76, 9 tables, January.

SIEBENROCK, F.

1902. Zur systematik der schildkrotenfamilie Trionychidae Bell, nebst der beschreibung einer neuen _Cyclanorbis_-art.

Sitzungsb. Akad. Wiss. Wien, 91(1):807-46, 18 figs., October.

1909. Synopsis der rezenten schildkroten, mit berucksichtigung der in historischer zeit ausges...o...b..nen arten. Zool. Jahrb., Suppl. 10, Pt. 3, pp. 427-618.

1924. Die nearktischen Trionychidae. Verh. Zool.-Bot. Ges. Wien, 1923, 73:180-94.

SIMKINS, C. S.

1925. Origin of the germ cells in _Trionyx_. Amer. Jour. Anat., 36(2): 185-213, 4 pls., November 15.

SIMPSON, G. G.

1943. Turtles and the origin of the fauna of Latin America. Amer.

Jour. Sci., 241(7):413-29, July.

SMITH, C. E.

1958. Natural History of Thomas County, Nebraska. Privately published, 99 pp.

SMITH, H. M.

1947. Kyphosis and other variations in soft-sh.e.l.led turtles. Univ.

Kansas Publ. Mus. Nat. Hist., 1(6):117-24, 1 table, July 7.

1956. Handbook of amphibians and reptiles of Kansas. Misc. Publ.

Univ. Kansas Mus. Nat. Hist., 2nd ed., No. 9:1-356, 253 figs., April 20.

SMITH, H. M., and JAMES, L. F.

1958. Taxonomic significance of cloacal bursae in turtles. Trans.

Kansas Acad. Sci., 61(1):86-98.

SMITH, H. M., NIXON, C. M., and MINTON, S. A., JR.

1949. Observations on constancy of color and pattern in soft-sh.e.l.led turtles. Trans. Kansas Acad. Sci., 56(1):92-98, 3 figs.

SMITH, H. M., and TAYLOR, E. H.

1950. An annotated checklist and key to the reptiles of Mexico exclusive of the snakes. Bull. U. S. Nat. Mus., 199:v + 253.