31 SYNOPSES AND DESCRIPTIONS. 



with brown, darker on throat and chin. A dark border to the lower edge 

 of the light line on the flank is not always present. A dark band passes 

 from the nasals through the eye to the neck. One of the specimens from 

 which this description is taken has been named by Prof, Jan Ilelicops 

 Agassizii. Hab, Mexico and Central America, 



Helicops allenii, pi. VII, Jig. 4. 



Garman, 1874, Proc. Bost. Soc. Nat. Hist., XVII, 92. 



Fusiform, stout, slightly compressed, belly rounded ; head small, crown 

 slightly convex and tapering to a point at the rostral ; tail moderate, taper- 

 ing rapidly near the base. Eye large, pupil round, situated in advance of 

 the middle of the length of the mouth. Mouth-cleft deep, slightly curved. 

 Posterior maxillary teeth larger. Head-shields eight. Internasals fused, 

 very small. Frontal slightly narrower forward. Occipitals broad, in con- 

 tact with the labials. Supraciliaries elongate, narrow in front. Prefrontals 

 broad, reaching down on the side of the face. Rostral small, broader than 

 high. Nasals entire, in contact between rostral and prefrontals. Nostril 

 small, superior, a groove from its lower edge to the labial. Loreal quad- 

 rangular. One anteorbital. Postorbitals three, lower small. Temporals 

 1+2 (not in contact with the orbitals). Labials 8, sixth and seventh large, 

 hinder angle of third and the fourth entering the orbit. Infralabials 10 

 (10 — 11), fifth and sixth larger. Submentals two pairs, hinder larger. 

 Scales smooth, excepting several rows on the tail, lustrous, in 19 rows, 

 vertebral twice as long as wide, outer wider than long, the medial two 

 rows of the tail strongly and the next pair slightly keeled. Ventrals 128. 

 Anal bifid. Subcaudals 58 pairs. 



Dorsal rows light reddish-brown (yellowish to flesh color on the flanks). 

 A vertebral band of rich dark brown near five scales in width, the middle 

 of which is perceptibly lighter. A band of lighter brown on each flank, 

 two scales and two half scales, separated from the vertebral by a band of 

 the ground color two half scales wide. Lateral edg~es of each scale darker. 

 Labials, chin and throat yellowish. Head of a uniform rich dark brown. 

 Florida. 



Hydrops. 



Wagler, 1830. 



Elongate fusiform to subcylindrical ; head rather indistinct, short, broad, 

 rounded; tail short, thick, pointed. Eye moderate, pupil round. Teeth 

 smooth, in continuous series, or posterior maxillary larger, sometimes iso- 



