54 HETERODON. 



Misdssippi.1 135+1.51.25. 10. IJ. Dr.B.F.Shumard. 



" ? D.C. Lloyd. 



SciotoYallcy,01uo.U^+\.^b.1b. 26. 4. | ^ x°^*^5-\ ^ 



(. Dr. J. P. Kirtland. 



2. Il-eterodon COg'na.tus, B. & G. — Vertical longer than occipi- 

 tals. Dorsal rows of scales 23-25 ; outer smooth; next scarcely carinated. 

 Scales of the rest vrith keels extending to their tips. Scales broader than 

 in preceding. Disproportion between scales of the back, before and behind, 

 not conspicuous. Light chestnut, with 20 yellow blotches from head to anus, 

 and 9 on the tail. Beneath yellow. 



Vertical plate pentagonal, elongated. Frontals moderate, of nearly 

 the same length. Azygos rather broad, similar in its relations to that 

 of H. jilati/rhinos. Rostral quite fully developed. Occipitals small, 

 less than in IT. platyrhinos. Scales back of head distinctly carinated. 

 Centre of eye above the middle of the 5th labial. Orbital chain of 

 10-11 plates. Loral rather large, triangular. Nasals moderate. 

 Labials 8. Penultimate rather longer than high. 



Scales diminishing in width towards the back, although not be- 

 coming as linear as in H. platyj-hinos. Scales on the hinder part of 

 back scarcely wider than those in front. 



Color above light chestnut, with transverse, sometimes more or 

 less oblique, dorsal bars between the 7th exterior rows. These bars 

 are bright yellow, tinged with brown in the centre, and with a darker 

 marginal shade of the ground-color. Of these bars there are 28, 

 from head to tail, the 20th opposite to the anus, each about ten scales 

 long, about nine broad, and separated by intervals of from four to 

 six scales. The proportional difference between the two colors in the 

 tail is much as in JI. platyrhinos. Color beneath clear dull yellow. 

 Exterior dorsal scales mottled brownish yellow, more or less spotted 

 and margined with brighter yellow. On separating the skin a dark 

 spot is seen at each end of the dorsal patches, between and around 

 which the color is yellow. Head olivaceous yellow, with the usual 

 markings of the genus obsolete. An elongated black patch behind 

 the angle of the jaws on each side. 



Somewhat similar to H. platyrhinos, but the scales anteriorly are 

 wider, nor is there that disproportion between the scales on-the back 

 before and behind. The occipitals are shorter. From H. atmodes, 

 the narrower intervals between the caudal light band, the scales cari- 



