On a case of Simous Malformation in a Snake. 399 



H. 



16 



20 



20 



21 



21 



A. Total number of vertebrte. B. Praecaudal vertebris. C. Ribless 

 anterior vertebrae, beaa-ing only epipleurals. U. Vertebrae with sessile 

 ribs and no transverse processes. E. Vertebi-ae with sessile ribs and 

 transverse processes. F. Vertebrae with ribs attached to transverse 

 processes. G. Praecaudal vertebrae with the trausverse processes united 

 to form a closed haemal arch, with or without htemal spine. H. Caudal 

 vertebrae. 



LVIII. — On a case of Simous Malformation in a Snake. 

 By G. A. BOULENGER, F.R.S. 



We have long been familiar with a curious monstrosity in 

 salmon and trout known as the " pug-nose," which consists 

 in the snout being aborted whilst the lower jaw retains its 

 normal development and projects forwards far beyond the 

 skull. I am now able to place on record a perfectly analogous 

 malformation in a Tropical American Opisthoglyph snake — 

 Stenorhina Degenhardti. 



The specimen, obtained by Mr. Underwood in Costa Rica, 

 is half-grown, measuring 330 millim. It will be seen from 

 the annexed figure that the snout is entirely absent and the 

 eyes strongly protrude in front ; the mandible, on the other 

 hand, is quite normal. 



c 



a, upper view of head ; b, side view ; c, front view. 



Whether the malformation in this case is congenital or 

 arose from an accident during life we have no means to tell ; 

 but, whatever may be its cause, it is a matter for wonder how 

 a snake should be able to maintain itself in that condition. 

 The power to secure its food must have been derived mainly 

 from the posterior grooved fangs, the portion of the maxillary 

 that supports them being, together with the pterygoids, all 

 that remains of the maxillo-palatal arch. 



28* 



