No. 112.J 15 



angular, truncated above. Nasals rather large, less developed than in H. 

 platyrhinos. Upper labials 8 ; 3d - 6th in contact with suborbitals. Centre 

 of eye above the juncture of the 4th and 5th. 



Scales distinctly carinated, except the outer row, which is smooth, and 

 the second, on which the carination is very obsolete, sometimes quite 

 smooth. All the scales diminish gradually to the back, where they are 

 quite linear ; posteriorly, however, they are broader. 



Color above and on the sides entirely dull black, beneath rather light 

 slate-color, shading into milk-white on the chin and on the edge of the 

 upper labials. The exterior row of scales shade gently from the color of 

 the back to that of the belly. 



The Heterodon niger bears quite a close relationship in the character 

 of the plates and scales to H. platy rhinos, from which the principal 

 difference lies in the color. Although this species greatly resembles in 

 color the black variety of H. atmodes, they may be readily distinguished. 

 The rostral of H. niger is well developed, high, broad, and with the dorsal 

 carina acute and well marked. The carination on the scales back of the head 

 is delicately distinct, as also upon the other scales, the keel extending to 

 the very tip. The scales on the back are linear and narrow, but become 

 much broader in proportion towards the tail. The occipitals are longer, 

 and the head in front of the eye longer in proportion to the part behind it. 

 No bands evident, even obsoletely. The other differs in all these respects : 

 rostral low, and the keel more rounded ; scales on back shorter, and ante- 

 riorly rather broad, and the disproportion with those posteriorly much 

 less conspicuous ; carinse not extending to the tip ; faint bars seen indis- 

 tinctly across the black of the back, &c. 

 Carlisle, Pa. ? 140+1. 49. 25. 36. 6. S. F. Baird. 



Specimens from the south differ simply in being rather darker on the 

 Bides and beneath. 



Abbeville, S. C. 145 + 1. — 25. 26. — Dr. J. B. Barratfc. 



Kempe county, Miss. 126+1. 53. 25. 28. 5|. D. C. Lloyd. 



