276 OPHIDIA. 



animals. Many have a distinctly prehensile tail, by means of which they hold on to pro- 

 jecting objects. Their food consists entirely of fish, and, in a few species, of Crustacea also. 

 All of them appear to be viviparous, and the act of parturition is performed in the water. 

 They do not grow to any considerable size, are of a gentle disposition, and their bite would 

 be by no means dangerous. They will not feed in captivity, and therefore die after a short 

 time. 



Spiopsis of the Genera. 



* Snout without appendage. 

 t Five upper labials. 



Scales smoothj iu from tweaty-five to twenty-nine series .... Fordonia, p. 276. 



Scales smooth, in nineteen series . Cantoria, p. 277. 



tt More than five upper labials ; ventrals not keeled. 



Occiput covered with scales Cei-berus, p. 278. 



Scales smooth ; one anterior frontal Hypsirhina, p. 280. 



Scales smooth ; two anterior frontals Ferania, p. 284. 



Scales keeled ; occiput shielded Homalopsis, p. 285. 



ttt Ventrals tvith two sharp ridges. 



Scales smooth Hipistes, p. 286. 



** Snout with a pair of tentacles. 



Ventrals very narrow, bicarinate Herpeton, p. 288. 



FORDONIA, Gray. 



Head depressed, short, broad, scarcely distinct from neck ; body stout, 

 cylindrical ; tail rather short, tapering-, longer in males than in females, thick 

 and strongly compressed in the former. Cleft of the mouth of moderate 

 width, not angularly bent behind. Eye small, with vertical pupil. The 

 whole upper surface of the head is shielded. Nostril directed upwards, in 

 the middle of a simple nasal shield. Anterior frontal siui^le, small, in con- 

 tact with the rostral. Five upper labials. Scales smooth, without apical 

 groove, in from twenty-five to twenty-nine series, those of the outer series 

 with truncated apex in adult specimens. Ventrals rather narrow, the two or 

 three last bifid ; subcaudals two-rowed. Maxillary short, with three or four 

 small teeth and with a longer grooved tooth behind ; mandibulary teeth very 

 short. Viviparous. 



Only one or two species are known. 



