426 PROCEEDINGS OF THE ACADEMY OF [1894. 



Hemipenis with two apical papillae; Ceratophnllus Cope. 



Hemipeuis without papilla; Diplophallas Cope. 



bh. Dentition diacrauterian. 



Hemipenis without papilla; Bothrodytes Cope. 



Trimerodytes balteatus gen. et sp. nov. Plate X, fig. 2. 



Char. gen. — Characters of Natrix, but the prefrontals fused. 

 The dentition is syncranterian or coryphodont. Hemipenis undi- 

 vided, sulcus simple. 



The single species on which this genus is proposed is represented 

 by an individual which, while apparently not very young, is at the 

 same time not fully grown. As a consequence the spinulfes of the 

 hemipenis are not ossified, appearing as fine flexible papillae. This 

 is the condition normal to immature snakes, as I have observed in 

 the genera Dryviobius, Bascanium, etc. 



Char, specif. — Scales in nineteen rows, smooth, except on the tail, 

 where all except the lateral rows are feebly keeled, and for a short 

 distance in front of the vent, where about three dorsal rows are also 

 weakly keeled. Each internasal longer than wide. Frontal rather 

 wide, with straight borders, the anterior a little longer than the 

 lateral. Parietal moderately elongate, angulate posteriorly, and 

 embracing only the superior postocular. Loreal higher than long ; 

 oculars 1-2 or 3; temporals 1-2. Superior labials nine. These are 

 differently distributed on opposite sides, so that the numbers may be 

 in other specimens, eight or ten. One labial forming most of inferior 

 border of orbit, which may be the fourth or fifth ; the angle of the 

 succeeding labial enters the orbit. On one side two plates represent 

 the single last upper labial on the other. Inferior labials nine; pre- 

 genials shorter than postgenials, and bounded by six labials. Gas- 

 trosteges , 202; anal, 1-1; urosteges, 84. 



Color black, crossed by white or pale yellow rings. These have 

 a width of half of a scale on the middle dorsal region, and widen 

 downward, covering two or three gastrosteges. They are frequently 

 broken on the middle line, the halves alternating, both on the back 

 and belly. The labials and oculars have yellow centers, and there 

 is a yellow line from near the angle of the mouth to near the middle 

 line above. A pair of yellow spots are on each side of the common 

 suture of the parietal plates. 



Total length, 377 mm. ; tail, 80 mm. 



