196 



CALIFORNIA ACADEMY OF SCIENCES. 



Description. Head flat-topped or rounded, with snout 

 projecting and rather nar- 

 row. Temporal regions 

 not swollen. Rostral plate 

 very large, prominent, 

 not very narrow, but often 

 recurved between interna- 

 sals on top of snout, and 

 bounded behind by inter- 

 nasal, anterior nasal, and first labial plates. Plates on 

 top of head, a pair of internasals, four, two, one, three, 

 five, six, or eight prefrontals, a 

 frontal, supraocular of each side, 

 and a pair of parietals. Anterior 

 and posterior nasals usually dis- 

 tinct, sometimes united. Loreal 

 usually elongate. One or two pre- 

 oculars and two to four postocu- 

 lars. Tips of some labials often 

 cut off, forming suboculars or lore- 

 als. Temporals four followed by 

 five, very variable. Seven to nine 

 superior and eleven to thirteen 

 inferior labials, next to last supe- 

 rior and sixth or seventh inferior 

 largest in its series, fourth or fifth 

 superior usually reaching eye, first pair of inferior meet- 

 ing on median line. Two pair of geneials, anterior 

 much larger than posterior. Scales on body in twenty- 

 seven to thirty-five rows, keeled except in a varying 

 number (about 3 to 10) of rows on each side. Anal 

 plate not divided. Gastrosteges varying in number 

 from two hundred and four to two hundred and forty- 

 five. Urosteges in two series of from fifty-six to sev- 

 enty-two. 



