A CRITICAL REVIEW OF THE CHARACTERS AND VARIATIONS OF THE SNAKES OF NORTH AMERICA. BY E. D. Cope. In the following paper the attempt is nnide to tlefine with preeision the species of Xoith American snakes, together with their variations. This may be done more satisfactorily than hitherto, since the material which has accumulated in our museums is now considerabh'. In mak-ing this investigation I have had the advantage of a full study of the specimens in the U. S. National Museum,* as well as those in other collections. So soon as sufficient material becomes available, the zoologist can make that kind of research into the permanency and variability of the characters of species which characterizes the exact stage of the science. It is on such studv that all useful conclusions as to the orisrin of species depends. It is not the orderly relation of species and genera to each other that demonstrates the truth of the hypothesis of the derivation of species, but the knowledge of their variations, ^loreover, the beginning of all investigation into the causes of those variations is the knowledge of the direction which they take, whether they aie promiscuous or whether they bear some detinitc relation to each other or to the environment. This being the object of this paper, I have not entered into any dis-cussion of systematic problems. 1 — CATODONTA. GLAUCONIA (ira.N . Catalojjno Lizards Brit. Mas., 1"M,">, i>. i;{l'. Sienoslomo Wa;;!., Nat. Sy.st. Aniphih., l'<W, nee LatreilliM, ISIO (Coleoptera). Leplottiphdjpii Stojnoj;t'r, Proc. U. S. Nat. Mas., 1801, 501 rafter Fit/.iager. nomen niiditiH^. Head slightly depressed an«l continuous with the l)ody. Sn»»ut blunt and rounded, overlapping considerably tiie lower jaw. A large rostr.jl plate. One nasal. A i)air of frontonasals. One ocular shiehl, which extends to the labial border. A pair of superciliaries, parietals and •I wish to oxpross hero the oblig.ntion nndor which I have lu. n pia. .d m\ in,. Otiicors of that institiitit>n, I'rofs. S. P. Laugloy ami (J H. U<hx1«>. PiVCoeiUiiRS Xatioual Mu»oani, Vol. XI V— No. S"C 5?9
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