13. COLUBRIDAE 



occur within the area under consideration by the number of 

 its gastrosteges and the position of the light nuchal collar. 

 The gastrosteges are more numerous than in T. nigrice-ps 

 and T. -planice-ps but fewer than in T. eiseni. The collar 

 does not involve the parietal plates in any of those species. 



Genus 44. Trimorphodon 



Trimorfhodon COPE, Proc. Acad. Nat. Sci. Phila., 1861, p. 297 (type, 

 T. lyrofhanes) ; COPE, Report U. S. Nat. Mus. for 1898, 1900, 

 p. 1101. 



The body is not much elongate, with tail of moderate 

 length. The head is wide, more or less triangular, and very 

 distinct from the slender neck. The snout is more or less 

 truncate. The head plates are normal. The nasals are 

 distinct. There are two loreals, one in front of the other. 

 The preoculars and temporals are numerous. The scales 

 are smooth, in 20 to 27 rows 5 often in an even number. 

 Posterior maxillary tooth elongate, grooved; anterior teeth 

 elongate; intermediate teeth shorter. The eye is large with 

 vertically elliptic pupil. 



This genus includes a number of Mexican species, only 

 one of which occurs within our geographic limits. 



204. Trimorphodon lyrophanes Cope 

 LYRE SNAKE 



Lycodon lyrophanes COPE, Proc. Acad. Nat. Sci. Phila., 1860, p. 343 

 (type locality, Cape St. Lucas, Lower California). 



Tr'morphodon lyrophanes COPE, Proc. Acad. Nat. Sci. Phila., 1861, 

 p. 297; COPE, Bull. U. S. Nat. Mus., No. i, 1875, p. 38; YARROW, 

 Bull. U. S. Nat. Mus., No. 24, 1883, pp. 15, 98; COPE, Proc. Amer. 

 Philos. Soc., 1886, p. 286; COPE, Bull. U. S. Nat. Mus., No. 32, 

 1887, p. 68; COPE, Proc. U. S. Nat. Mus., Vol. XIV, 1892, p. 679; 

 VAN DENBURGH, Proc. Cal. Acad. Sci., Ser. 2, Vol. 5, 1895, p. 155; 

 MOCQUARD, Nouv. Arch. Mus. Hist. Nat., Paris, Ser. 4, Vol. I, 

 1899, p. 330; COPE, Report U. S. Nat. Mus. for 1898, 190x3, p. 1102; 



