304 PROCEEDINGS OF THE ACADEMY OF 



Loxocemus bic olor Cope, Pr. Ac. Nat. Sci. Phila. 1861, p. 76. 



This genus, discovered in Guatemala by Capt. Dow, seems to confirm by its 

 structure the propriety of the arrangements of Muller and Dumeril, in which 

 the Peropoda or Aproterodonta is regarded as an equivalent of the other 

 subordinate divisions of the Colubridas or non-venomous Eurystomata. 



According to Prof. Reinhardt, nearly all the genera of Boinas have uniporous 

 scales ; in Loxocemus they are poreless, as in the Calamarinse. Other resem- 

 blances to these serpents have been previously pointed out, loc. sup. cit. The 

 os postfrontale is elongate falciform, articulated at its proximal extremity 

 with an anterior prolongation of the os parietale, and slightly with an os su- 

 praorbitale. Between the latter bone and the os frontale a second superor- 

 bital is intercalated. The presence of these bones, together with the biserial 

 urosteges, constitute points of affinity with the Pythons. The os mastoideum 

 and o. quadratum are short and stout. The o. nasalia are slightly contracted 

 by the production of the o. prefrontalia, but again expand, and unite with the 

 o. frontale by an extensive suture. These two points are Erycine. The Boi- 

 nffi seem, therefore, to be divisible into four subgroups the Pythones, the 

 Boae, the Loxocemi and the Eryces. The osseous structures typical of these 

 groups are : 1st, supraorbital bones and a dentigerous intermaxillary ; 2d, no 

 supraorbitals or intermaxillary teeth ; prefrontals which separate the nasals 

 from contact with the frontals, (observed in Enygrus, Ungalia Homalochilus, 

 Boa, Chilabothrus, Eunectes, Epicrates, Xiphosoma) ; 3d, supraorbitals present, 

 iatermaxillary edentulous, nasals articulating broadly with frontals, suspenso- 

 .ria short, stout ; 4th, no supraorbitals or teeth on the intermaxillary ; nasals ar- 

 ticulating broadly with frontals, suspensoria short, stout. 



Lichanura trivirgata Cope. 



The genus Lichanura may be diagnosed as follows : 



General form abbreviated and stout ; tail short, thick, obtuse at the ex- 

 tremity. Head slightly distinct, elongate, subcompressed ; muzzle rather con- 

 stricted ; eye small, pupil vertical. Rostral plate elevated ; nostril between 

 two plates, the. anterior in contact with that of the opposite side, upon the 

 median line. Posterior to these the upper surface of the head is covered with 

 smooth scales. Labial plates without pits. Scales smooth, broad, poreless. 

 Spurs conspicuous. Gastrosteges narrow. Fronto-nasal suture extensive. 



This genus of Eryces differs from Cusoria Gray in its elevated rostral plate 

 and its two nasal plates. In Cusoria there are three of the latter, and a de- 

 pressed rostral. The form, etc., of the head is somewhat similar to that of 

 Homalochilus among the true Boae, which, however, possess a nostril bor- 

 dered by three shields. Acrantophis Jan., the true position of which it would 

 be interesting to know, appears to be an ally. The irregular squamation of the 

 superior surface of the muzzle the acute tail, and partially divided urosteges 

 of that genus, separate it. 



L. trivirgata inhabits the southern region of Lower California, where 

 Mr. J. Xantus has obtained it for the Smithsonian Institution (Nos. 2277 and 

 2287) and the Academy. He found it in swamps among the mountains. Its 

 scales are in forty longitudinal rows, the inferior a little larger than the others. 

 Ten scales in the ocular ring : superior labials fourteen or fifteen, the anterior 

 three highest. Loreals, three superior vertical, two inferior horizontal. Ros- 

 tral plate prominent, elevated, recurved, quinquelateral, its labial border as 

 long as its nasal. Inferior labials fifteen, the anterior five longest. A short 

 mental fissure. Total length 25 in., tail 4 in. 



General color pale yellowish, tinged above with brown. The belly and 

 flanks are irregularly specked with liver brown. Superiorly there extend from 

 the muzzle to the end of the tail three deep liver brown bands, the median four, 

 and the two lateral, five scales wide, separated by intervals three and a half 

 scales in width. 



[Sept. 



