THE UNIVERSITY OF KANSAS SCIENCE BULLETIN Vol. XXVJ June 1,1938 [No. 16 On Mexican Snakes of the Genera Trimorphodon and Hypsigiena EDWARD H. TAYLOR, Departnu'iit of Ziiol(ig;\\ I'niveisity of Kansas (Plates XXXV-XXXin, Text fig. 7) Abstract: This study is based on specimens collected in Mexico by Edward H. Taylor and Hobart M. Smith. The followinq; species of Trijnorphodon are recognized: Trimorphodon bi-scatatus Dumeril and Bibron : paucnnacidatus Taylor; lambda Cope; vilkinsonii Cope; lyrophanes (Cope); vandenburghi Klauber; lalijascia Peters; upsilon Cope; and tau Cope. Hyp^iqloui placed in synonymy of Lcptodcira is again validated, and recog-nized as distmct on the basis of ungrooved back teeth, single instead of double apical pits, together with reduced \-ertebral series, and other characters of per-haps lesser importance. The following forms are recognized: Hypsigiena torquata torqnnta Giinther; torquata dunklci subsp. nov., Tamaulipas, Mexico; ajfinis Bouleuger, and ochrorhynchus Cope. Trimorphodon Cope Dipsas (pt.rt.) Dumeril and Bibron, Erp. Gen., Vfl, 1854, p. 1133 (/). bi-snitata Dumeril and Bibron). Dipnadomorplius (part.) Giinther, Cat. Col. Snal<es British Mus.. 18.38, p. 174 (D. bi-scutata, Dumeril and Bibron). Trimorphodon Cope, Proc. Acad. Nat. Sci. Philadelphia, 1861, p. 297. (lyroplianes Cope). Eteirodipsas (part.) Jan, Elenco sist. Ofid., 1863, p. 105. Siboii (part.) Garman, Mem. Mus. Conip. Zool. Harvard College, VIH, No. 3, p. 16. The group of back-fanged snakes belonging to this genus is char-acterized by greatly enlarged anterior maxillary teeth followed by smaller teeth which decrease somewhat posteriorly, and are followed after an interspace by a pair of enlarged, grooved fangs; anterior mandibular teeth and, to a lesser extent, the anterior palatine teeth, enlarged; head distinct from neck; two pairs of chinshields, the an-terior largest; seven or eight scale rows between first ventrals and posterior lower labial; two loreals present, and frequently a third, which is situated below the posterior; nasal divided, the nostril ver-tically elongate; pupil elliptic; eye moderate, less than the distance (357)
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