428 Dr. A. Gunther on Psammophis Perroteti. 



and shorter teeth. The spinous process of the body is of extra- 

 ordinary length ; the caudiform appendage, which is still but 

 little developed, terminates in a pointed extremity bent upwards. 

 The length of the larva is 3 millim. 



EXPLANATION OF PLATE VII. 



Fig. 1. Larva, probably of a Balanide, seen from above. Of the swim- 

 ming feet, only the middle pair and one of the anterior are seen 

 extended : a, carapace ; b b, horns of the carapace ; c, eye ; 

 d, spinous process of the body ; e, caudiform appendage of the 

 body. 



Fig. 2. Very young larva of a Cirripede, probably a Lepadide ; from the 

 back : a to e, as in fig. 1 ; /, alimentary canal. 



Fig. 3. A portion of the body of the larva of Lepas anatifera after the 

 first moulting, strongly magnified : a, central mass of the nervous 

 system ; b, ocellus ; c c, the two horns of the carapace. 



LIV. — Note on Psammophis Perroteti, D. fy B. 

 By Dr. Albert Gunther. 



[With a Plate.] 



Dumeril and Bibron have omitted several important characters 

 in their description of this remarkable snake, which is a truly 

 intermediate form between Psammophis and Dryophis. One of 

 its most important characters appeared to me to be the keeled 

 scales of the coccygeal region * ; but as nothing of it is men- 

 tioned by the French herpetologists, I failed to recognize the 

 first specimens which came under my observation, and described 

 them as a new species — Dryophis tropidococcyoc. The latter 

 specific name has been chosen with the view of its serving 

 as the name of the genus, if the snake should be considered as 

 a peculiar type. It cannot be referred either to Psammophis or 

 to Dryophis without disturbing the natural characters of those 

 genera ; whilst, as a separate genus, it may be placed in the 

 family of Dryophida, the characters being rather more in favour 

 of its relation to this family than to the Psammophidce. 



Tropidococcyx. 



Habit and physiognomy of Psammophis. Scales smooth, 

 those of the coccygeal region keeled. Rostral shield far pro- 

 duced backwards. A single nasal, pierced by the nostril ; pos- 

 terior nasal and loreal absent, replaced by the anterior and 

 posterior frontals, which are bent downwards on the side of the 

 head. Pupil horizontal {Dryophis). The fifth of the anterior 

 maxillary teeth and the hindmost longest, the latter grooved. 



* A similar peculiarity occurs in Aspidura trachyprocta, Cope, and 

 Trachischium, Gthr. 



