173 THE ZOOLOGIST. 



III. BoiDJi. A spur (rudiment of hiud limb) on each side of the vent. 



Scales very small, more than fifty across the body ; belly shielded. 



Pupil linear, erect. 



A single genus. Python. 



IV. CoLUBRiD^. Head with large symmetrical shields. Belly shielded. 



No grooved maxillary fangs anteriorly. 



A. Subcaudal shields in a single row, like the ventrals ; eye very small, 



with round pupil. Uriechis. 



B. Subcaudals divided. 



1. Scales smooth, equal ; pupil round. 



a. Eostral shield very large, with horizontal cutting edge. 



Temnobhynchus. 



b. Rostral without cutting edge. 



«. Nostril pierced between two shields, the second of which 

 touches the eye. .... Chokistodon. 



/3. Two or more shields on a line between the nostril and 

 the eye. 

 =:= Loreal shield (between nasal and prseocular) not much 

 longer than deep. 

 15 scales across the middle of the body. - - Homalosoma. 

 27 or 29 scales across the middle of the body. - Coronella. 

 17 or 19 scales across the middle of the body. Psammophylax. 

 *t- Loreal shield at least twice as long as deep ; 15 or 17 

 scales across the middle of the body. 

 Snout pointed and strongly projecting beyond the lower lip ; 

 tail not five times the length of the head. Rhamphiopuis. 

 Snout long and obtuse ; tail long ; frontal (interorbital) shield 



narrow. Psammophis. 



Snout obtuse; colour green. - • - Philothamnus. 



2. Dorsal scales keeled. 



Eye extremely large, with round pupil ; vertebral scales broader 



than the others, unicarinate. - - . - Bucephalus. 

 Eye very large, with horizontal pupil. - - Dryophis. 

 Eye moderale ; vertebral scales broader than the others, 



bicarinate. ...... Heterolepis. 



Eye moderate, with vertical pupil ; scales equal. Dasypeltis. 

 3. Scales smooth ; pupil vertically elliptic. 



a. Head broad, considerably broader than the neck ; 19 scales 

 across the middle of the body. - - Leptodika. 



h. Head not very distinct from the neck. 

 Nostril in a single nasal; 17 scales across the middle of the 



body. ....... Lycophidium. 



Nostril between two nasals; 19 to 23 scales across the middle 



