CROCODILIANS, LIZARDS, AND SNAKES. 



857 



The C. triaspis is a very different snake, having somewhat tlie appear- 

 ance of a Trimorphoilon in the form and color pattern of its head. Like 

 the third Mexican si^ecies of Coluber, the G.Jiavirufus Cope, it is an 

 inliabitant of the Tiorra Calienta. 



( 'oluber mutabilis Cope. 



Number 

 of speci- 

 mens. 



Locality. 



Vera Paz.. 

 Oaxaca . . . 

 Costa Rica 



Froiu whom received. 



Nature of specimen. 



Henry Hague 

 F. Sumichrast 

 P. Zeledon 



Alcoholic, 

 do. 

 do. 



COMPSOSOMA Dumeril and Bibron. 



Compnosoma Dumeril aiul Bibron, Erp. G6n., VII, 18.54, p. 290. — Cope, Trans. 



Amer. Phil. Soc, 1895, p. 204. 

 Spilotes Wagler, part, Naturl. Syst. d. Amphibieii, 1830, p. 179. — Dumi^ril and 



Bibron, Erp. G«5n., VII, 1854, p. 248. — Gunther, Cat. Col. Snakes Brit. Mus,, 



18.58, p. 96.— Cope, Bull. U. S. Nat. Mus., No. 32, 1887, p. 56. 

 Georgia Baird and Girard, Cat. N. Amer. Kept., Pt. 1, Serp., 1853, p. 92. 

 Phrynonax Cope, Proc. Acad. Nat. Set. Phila., 1862, p. 348. — Boui.enger, Cat. 



Snakes Brit. Mus., II, 1894, p. 18. 



Teeth of equal lengths. Head plates normal; two nasals, one loreal 

 and one j^reocular. Scales in an odd number of rows, bifossate. Anal 

 plate entire; subcaudal scuta divided. Pupil round. 



This genus embraces the largest ground snakes of the Neotropical 

 realm, together with a number of species of smaller size of the Paleo- 

 tiopical. It differs from Coluber in its entire anal plate, resembling in 

 this respect Pityophis, Epiglottophis, and Ehinechis. It approaches the 

 last named most nearly in characters, but the rostral shield has not 

 the production anteriorly and posteriorly seen in that yenus. 



The Asiatic si)ecies have a compressed form of the body which is not 

 seen in the American forms. Some of the latter have a roof-shaped 

 body with subtriangular section {G. sulphureuni), while in others (8. 

 corais) the body is subcylindric. The scales assume a slightly trans- 

 verse direction in some of the American species. But one species is 

 found in the United States, and this is a Neotropical species which 

 ranges from Brazil through Mexico and the Gulf States to the Atlantic 

 coast. 



It may be found necessary to separate the American species from 

 this genus, as has been done by Boulenger, under the name of Phrynonax 

 Cope. I do not at present, however, know of any character which 

 requires this. The difference of dentition pointed out by Dr. Boulenger 

 isinsigniiicant,ashis definition indicates. Theintegrity of theanal plate 

 is a definite character that can always be observed, which is more than 

 can be said for the slight differences of dentition referred to. The 

 character of the anal plate is not (piite constant in one of the Asiatic 

 species [C. virgatum), according to Boulenger. 



