hyoid apparatus formed of two or three pairs of bones; penis broad, expanded and pentifid, sulcus spermaticus quadrifid having branches in each of four lateral projections (Hoffman, 1890:298, pl. 47, fig. 2); aquatic, principally in fresh water; mainly carnivorous; flesh of many species eaten. (See Boulenger, 1889:237-41; Loveridge and Williams, 1957:412; Romer, 1956:513; Smith, _op. cit._:147-54). _Recent distribution_ (Figure 1).--North America, from extreme southeastern Canada and eastern United States west to Rocky Mountains and south to northern México; introduced in southwestern United States (Conant, 1958:69-73). Africa, from Egypt and Senegal south to Angola and Zambesi River drainage (Loveridge and Williams, _op. cit._:412-68); occurrence of _Trionyx triunguis_ in Syria (Boulenger, _op. cit._:255) and coastal streams of Palestine (Schmidt and Inger, 1957:36) considered accidental by Flower (1933:753-54). Southwestern Asia (Tigris and Euphrates River drainage) in eastern Turkey, Syria, Iraq and northeastern Israel (Mertens and Wermuth, 1955:388). Southeastern Asia, from Pakistan and India (Indus River drainage) and Manchuria and adjacent Siberia (Amur River drainage) to Ceylon, Japan, Formosa, Hainan, Luzon, Sumatra, Java, Borneo, Timor and southeastern New Guinea (De Rooij, 1915:325-32; Okada, 1938:108; Pope, 1935:60-64; Smith, 1931:158-79; Stejneger, 1907:514-532; Taylor, 1920:141). _Trionyx cartilagineus_ is questionably recorded from the Moluccas (De Rooij, _op. cit._:330). _T. sinensis_ has been introduced on Kauai Island, Hawaiian Islands (Brock, 1947:142; Oliver and Shaw, 1953:83), one of the Bonin Islands (Okada, 1930:187-94), and probably Timor (De Rooij, _op. cit._:331). All insular records east of Borneo and Java are probably the result of introductions, except perhaps those of _Pelochelys_ on Luzon and New Guinea (Darlington, 1957:210). [Illustration: FIG. 1. Geographic distribution of the family Trionychidae.] _Recent genera._--According to Mertens and Wermuth (1955:387-95), there are 21 species belonging to six genera as follows: _Chitra_ Gray, 1844 (1) _Cyclanorbis_ Gray, 1854 (2) _Cycloderma_ Peters, 1854 (2) _Lissemys_ Smith, 1931 (1) _Pelochelys_ Gray, 1864 (1) _Trionyx_ Geoffroy, 1809 (14) _Dogania_ is considered a synonym of _Trionyx_ (Loveridge and Williams, _op. cit._:422). _Geologic range._--Lower Cretaceous (possibly Upper Jurassic) to Recent of Asia; Upper Cretaceous to Recent of North America; Paleocene (Upper Jurassic, assuming _Trionyx primoevus_ is a trionychid) to Pleistocene of Europe; Lower Miocene to Recent of Africa; Pleistocene to Recent in East Indies (Loveridge and Williams, _op. cit._:412; Romer, 1945:594); questionable trionychid fragments from Pleistocene of Australia (Darlington, _loc. cit._). $/