298 PROCEEDINGS OP THE ACADEMY OP 



the scales themselves obtuse, (subemarginate in G r a h a m i i ), in nineteen 

 rows. There are nine superior labials, eye over the fourth and fifth, (six or 

 seven inGrahamii, eye over third and fourth), one or two preocular, and 

 two or three postocular plates. The head is shorter and broader than in 

 Grahamii, hence the loreal is higher than long, instead of longer than 

 high. The external nares have a more vertical aspect, but resemble those of 

 Grahamii and of Tropidoclonium sp. in being connected by suture with the 

 labial border only. The prefrontal plates are frequently confluent as des- 

 cribed by Boie. Inferior surface uniform yellow; no median caudal band. 

 Size that of T. 1 e b e r i s. 



Tropidonotus v a 1 i d u s Cope, Pr. A. N. S. Phil. 1860, p. 342. Regina valida 

 Kenn. 1. c. 1860, p. 334. Tropidonotus tephropleura Cope, 1. c. 1860, p. 341. 

 The Californian and Durangoan specimens, assigned formerly to distinct spe- 

 cies, differ in little more than in the less elongated head of the latter. A spe- 

 cimen from Utah in Mus. Smithsonian is quite intermediate in this respect, 

 proving that they are not worthy of receiving distinct appellations in the system. 



Tropidonotus c else no Cope, Pr. Ac. Nat. Sci. Phil. 1860, p. 341. 



Inhabits Cape St. Lucas, Lower California. This species and the preceding, 

 the only members of the genus inhabiting the Pacific region of North America, 

 have the number of rows of scales similar to that characterizing the European 

 and Asiatic species, while our Eastern and Southern species of the s i p e d o n 

 type, are different in this respect. They agree in the absence of scale pores 

 with the American species of the type of 1 e b er i s, and the stolatus and 

 quincunciatus types of Asia. According to Mr. Xantus they are most 

 common in swampy meadows among long grass. 



Tretanorhinus nigroluteus Cope. Dorsal scales in twenty-one rows, all 

 keeled. Head slightly distinct, narrow. Rostral plate broader than high, 

 separated from the prefontals by the nasals : each of the latter is subtrans- 

 verse, the nostril between. Postfrontals as long as vertical ; anterior border 

 of the latter equal to the lateral :occipitals elongate, each bounded by seven 

 temporals. Two loreals, anterior smaller ; two preoculars, the superior 

 smaller, not in contact with the vertical; two postoculars, in contact with the 

 temporal. Eight superior labials, eye resting on the fourth ; inferior labials 

 ten, the sixth elongate, the tenth very small. Two pairs of postabdominal 

 scutella. Gastrosteges 136 (tail mutilated) ; length of body 15 in. 6 lin. 



Color above black, tinged with plumbeous as far as the superior half of the 

 second row of scales ; below yellow, punctulated anteriorly, especially upon 

 the inferior labials. Upon the anterior third of the body, the punctulations 

 form a narrow band upon the extremities of the gastrosteges, separated from the 

 dorsal black by a narrow yellow band. A few irregular spots on the urosteges. 



One specimen (5568) presented to the Smithsonian Inst., by Dr. Caldwell, 

 from Greytown, Nicaragua. 



This species differs from the T. v a r i a b i 1 i s D. & B. in color, in the 

 greater relative size of the postfrontals, and in the presence of carinse upon 

 all the more elongate scales. In both the Tretanorhini, the scale-pores are 

 absent. Cuba is the native country of the T. variabilis, whence it does 

 not seem to have been often sent. Dr. Lobi has presented it to the Academy, 

 and Prof. Poey to the Smithsonian Inst. It is an interesting species, as 

 exhibiting fhe full development of the structure towards which we see a suc- 

 cessive approach in Tropidonotus rhombifer,* T. ustus, T. cyclo- 



* Since this species was first made known by Dr. Hallowell, it has been described as 

 Tropidonotus pogonias and Nerodia holbrookii ; it is also very possibly T. cyclopion 

 of Giinther. The mental tubercles do not constitute a specific peculiarity, but are most 

 common on all old individuals : they occur on both species of Tretanorhinus. T. rhom- 

 bifer inhabits the Mississippi valley as far north as Southern Illinois, where Mr. 

 Kennicott has obtained it. 



[Sept. 



