186 [October, 



Besides these, there are four species described by others which I have never 

 seen, namely, K. hirtipes Wagler. descript. et icones. tab 630. K. brevicau da- 

 tum Spix. Rept. Braz. p. IS, tab. xiii. K. cruentatnm Cat. Mus. Jardin des 

 plantes, and K. Doubledayii Gray, Cat. Brit. Mus. 



In the imperfect monograph of the Tortoises of the United States, published 

 in the Annals of the Lyceum of Natural History of New York for the year 1829, 

 I complained that no arrangement of these animals had yet been offered to the 

 world which I could consent to adopt. This defect has not yet been remedied, 

 nor since then have the various suggestions offered by different naturalists been 

 at all satisfactory. Every scheme for the arrangement into families and groups, 

 has evidently not been founded on natural and philosophical principles. Most 

 writers on Herpetology appear to have devoted their time, not to the dis- 

 covery of the affinities of the objects they were describing, but to changing the 

 names of the genera and the species, and to making sppcies out of the slightest 

 varieties; thus clogging the science with useless and absurd synonyms. 



The simplicity of my arrangement, which divides the whole order into four 

 great families, and-these again, when necessary, into groups, will 1 hope recom- 

 mend it to notice. I owe this arrangement, in a great degree, to the suggestions 

 of my son. 



FAMILIA PRIMA. 



Pedes penniformes. Sternum osse episternali postice producto. 



1. Chelone Brog. Corpore scutato. Sternum scutellis pluribus a testa seiunc- 

 tum. Caretta Merr. et Bon. Coriudo Flem. Thaiassochelys Fitz. 



2. Sphargis Merr. Cute coriacea. Coriudo Flem. Dermatochelys, Blainv. 

 Scytina Wagl. 



FAMILIA SECUNDA. 



Pedes compressi, ungulati. Sternum scuto singulo (abdominal i) alato, alarum 

 marginibus non infiexis. 



A. 



Sternum osse episternali postice producto. 



1. Chelvdra Schw. Corpore scutato. Sterno scutis 10; abdominalibus luxatis 

 alas formantibus. Chelonura Flem. Rapara Gray. Saurochelys Lat. Emysaurus 

 Dum. 



2. Staurotypus Wagl. Corpore scutato. Sterno antice mobili, scutis septem, 

 brachialibus et gularibus nullis, anali unico. 



3. Trionyx Geof. Cute coriacea. Ossibus marginalibus nullis. Gymnopus Dum. 

 Amyda Schw. Playtpeltis Fitz. Pelodiscus eiusdem. 



4. Emyda Gray. Cute coricea ; ossibus marginalibus distinctis. Trionyx Wagl. 

 Cryptopus Dum. 



B. 



Sternum plus minus uni-vel-bivalve, osse episternali maximo, entosternaU 

 obsoleto (in pullis rudimentali) alis a scuto abdominali solum proiectis. 



1. Kinosternum Wagl. Alis scutellis duobus addititiis, sterno scutis 11. 

 Staurotypus in parte Dum. Stemothcerus in parte Bell. Cistudo Say. 



FAMILIA TERTIA. 



Pedes ungulati plerumque compressi. Sternum scutis duobus alatis (pectorali 

 abdominalique ;) alarum marginibus, excepta Cistudine, fortiter infiexis; scutis 

 caudalibus duobus distinctis. 



st. Sternum scutis 11 s. 12 tectum ; unguibus 5-5, 4-5, 4-4, vel 4-3. 



1. Emys. Sterno solido sutura laterali ossea, scutis gularibus duobus. Alis 

 scutellis duobus addititiis. Unguibus 4-5 vel 4-4. Includitur genus Lessonianum 

 Tetronyx. Khinoclemys Fitz. Terrapene Bon. Clemmys Wagl. Geomys Gray. 



2. Platysternum Gray. Sterno solido, sutura laterali ossea, scutellis tribus 

 addititiis a scutis marginalibus seiunctum. 



