18G0.] ^^^ [Cope. 



Nasals different in size, the anterior much smaller and not more elevated 

 than the loreal. Muzzle very narrow, internasals longer than broad, 

 vertical elongate and contracted by the concave superciliary sutures, its 

 anterior suture one-half its length, which equals the common occipital 

 suture. Occipitals emarginate behind. Gastrosteges 201, 201, 204, 210 ; 

 anal { ; urosteges 100, 122, 108, 100. Length 37.25 inches, of which the 

 tail measures 3.25 inches. 



Color, dark slate brown above, with a number of blackish cross-bands 

 behind the head, which are sometimes quite indistinct and sometimes 

 separated by paler bands. A broad brown band from the nostril through 

 the eye which expands and is lost on the temporal region, though its 

 lower boundary is continued as a line on the side of the neck. The 

 scales on the median dorsal line have a white border. Belly, the 

 posterior half black, anterior yellowish, gray spotted. Upper labial 

 region orange, brown spotted ; gular region grayish brown and orange 

 mingled. Frontal and occipital plsttes dark medially. This species is in 

 general appearance much like the A. sanctaecrucis, but it has the loreal 

 plate of the A. angulifer, and several more series of scales than either. 

 The frontal shield is of a narrower form than in either A. sanctaecrucis or 

 A. antillensis. 



Habitat. So far as yet known, this distinct species is confined to the 

 small island of St. Martins, in the Spanish West Indies, which has an 

 area of only about thirty square miles. Six specimens were sent to the 

 Academy Natural Sciences by Dr. R. E. Van Rijgersma of that island. 

 I dedicate the species to him in recognition of his labors in endeavoring 

 to lay a basis for the complete zoology of that island. 



Xenodon isolepis, C(?pe. 



Eight superior labials, fourth and fifth entering orbit, sixth the largest, 

 exceeding the seventh. Anal shield bifid. Scales of the body in nine- 

 teen series quincuncially arranged of equal size and form, one pitted. 

 General arrangement that of a Coluber ; the body is also as in that type 

 entirely cylindric. Oculars 1-2 ; loreal little higher than long ; postnasal 

 highest ; rostral not prominent. Temporals 1-2. Frontal longer than 

 wide, longer than occipital. 



Gastrosteges 156 ; urosteges 55. 



Color uniform leaden above, flanks greenish, below dirty white. Pos- 

 terior tooth rather short. This species is nearest in technical characters 

 to the X. neovidii Gth. but differs entirely in color, and the equal size 

 and form and quincuncial arrangement of the scales. The sixth upper 

 labial is according to Gunther's figure (Ann. Mag. Nat. Hist., 1863, V. 

 C.,) much smaller than the seventh ; here the latter is distinctly smaller 

 than the former. 



From Pebas Equador on the upper Amazon. Eeceived from Professor 

 James Orton, of Vassar College, New York. A collection recently re- 

 ceived from that gentleman from the same locality embraced the follow- 

 ing species, all of which are in the Museum of the Academy Natural 

 Sciences, presented through the liberality of Prof. Orton. 



