1. CHELYs. 207 
Synopsis of the Genera. 
1. Neck longer than the dorsal vertebral column ; jaws weak. 
Nose ending in a tube; fore limb with five claws, hind limb with 
four: a broad parieto-squamosal arch; neural plates present. 
1. Chelys, p. 207. 
Both fore and hind limbs with four claws; nuchal shield behind the 
marginals, simulating a sixth vertebral; a slender parieto-squa- 
mosal arch; neural plates present .. 2. Hydromedusa, p. 210. 
Both fore and hind limbs with four claws; intergular shield behind 
the gulars ; no paricto-squamosal arch ; no neural plates. 
3. Chelodina, p. 213. 
II. Neck shorter than the dorsal vertebral column. 
A. Lower jaw narrow at the symphysis; first-vertebral shield 
larger than second. 
Neural plates present; parietal bones not expanded superiorly ; 
parieto-squamosal arch very slender.. 4. Rhinemys, p. 217. 
Neural plates present ; parietal bones expanded superiorly ; parieto- 
squamosal: archystrom@ “7... <.6 4s 5. Hydraspis, p. 219. 
Neural plates absent; parietal bones much expanded superiorly ; 
vertebral region grooved .......... 6. Platemys, p. 226. 
B. Lower jaw, at the symphysis, at least as broad as the orbit ; 
first vertebral shield not larger than the second. 
Alveolar surface of upper jaw without median ridge. 
7. Emydura, p. 228. 
Alveolar surface of upper jaw with a median ridge. 
8. Elseya, p. 234. 
1. CHELYS. 
Chelys, Dumér. Zool. Anal. p. 76 (1806); Fitzing. N. Classif. Rept. 
p- 7 (1826); Wagler, Syst. Amph. p. 154 (1880) ; Gray, Syn. Rept. 
p. 43 (1831); Dum. § Bibr. i. p. 454 (1855); Gray, Cat. Tort. 
p. 44 (1844), and Sh. Rept. i. p. GO (1855); Strauch, Chelon. 
Stud. p. 49 (1862); Gray, Suppl. Cat. Sh. Rept. i. p. 71 (1870). 
Matamata, Merrem, Tent. p. 21 (1820). 
Neural plates present, seven in number, the last pair of costals 
forming a suture ; nuchal shield present, marginal ; plastron narrow, 
with very strong axillary and inguinal buttresses, the latter anchy- 
losed to the fourth costal plate. Neck longer than the dorsal 
vertebral column. No separate nasal bones ; a strong supraoccipital 
