292 BULLETIN 58, UNITED STATES NATIONAL MUSEUM. 



cially in front, their suture with the rostral being shorter than that of 

 the latter with first supralabial ; prefrontals broadly in contact with 

 supraoculars; frontal shorter than its distance from tip of snout, 

 scarcely ecjualino; the interprefrontal suture, with nearly parallel sides; 

 supraoculars narrow, scarcely more than half as wide as frontal ; pari- 

 etals much longer than distance of eye from tip of snout, as long as 

 frontal and prefrontals together; nostril small, round beliind the mid- 

 dle and near the upper edge of the nasal Avhich is only divided into two 

 unequal parts below the nostril; loreal nearly rectangular, slightly 

 longer than high; one preocular, widely separated from frontal; eye 

 small; three postoculars, the lower one almost horizontal; temporal 

 2 + 3, those of the first row ver^^ long and the upper especially very nar- 

 row; eight supralabials, fourth entering eye; five lower labials in 

 contact with anterior pair of cliin-shields, which are considerably 



255 



Figs. 253-255.— Natrix annularis. 2 x nat. size. 253, top of head: 254, side of head (.^Hx nat 

 SIZE); 255, rostral from front. No. 34044, U.S.N. M. 



shorter than posterior, chin-shields and labials studded with numer- 

 ous small, rounded tubercles; 19 rows of scales, with two somewhat 

 obscure apical pits, striated and strongly keeled, except outer row, 

 which is feebly keeled; 163 ventrals; anal divided; 61 pairs of sub- 

 caudals. Color (in alcohol) on back dark grayish drab with ill-defined 

 black reticulations or series of small ill-defined, alternating ])lack 

 spots ; sides gradually much paler toward the ventrals, with numerous 

 vertical black bars about two scales wide and two scales apart, the bars 

 continued on the ventrals joining the corresponding ones of the other 

 side as half- rings or alternating with them ; scales included in black 

 lateral bars with pale centers; shields on head obscurely outlined with 

 dusky; labials whitish, with blackish sutures both on upper and lower 

 lip, except on suture between fifth and sixth supralabials ; an obscure, 

 oblique blackish postocular streak; lower parts pale vinaceous-cinna- 

 mon, with black half-rings. 



