ART. 12 REVISION OF LIZARDS OF GENUS CTENOSAURA BAILEY 49 



Type.— Three cotypes, U.S.N. M., male No. 12282, Yucatan. A. 

 Schott, collector. 



Type locality. — Restricted to Chichen Itza, Yucatan, Mexico. 



Diagnosis. — Tail short, almost flat, covered with whorls of strong, 

 erect, conic spinous scales, which are not separated by rows of smal] 

 flat scales. Scales on femur and tibia are spiniferous and larger than 

 those of the fore limbs. Dorsal crest barely noticeable, being made 

 up of slightly carinated scales, and extending from the nape to the 

 beginning of the sacrum. Scales on the rump larger than those on 

 body. Digits shortened. 



Distribution. — This lizard is known only from Yucatan, Mexico. 

 It is a ground-dwelling species and is most abundant on the desert 

 and somiarid limestone plains of the peninsular, having been taken 

 at Chichen Itza. 



Description. — M.C.Z. No. 7095, adult female. Head normal in 

 length, covered with fairly large scales, having slightly decurved 

 muzzle. Scales of head somewhat convex, those on muzzle being 

 larger than others; supraoculars smaller than parietals, separated 

 from each other by three rows of scales; nostril on canthus rostralis, 

 lateral; loreal region concave. Supralabials 7; sublabials 7; ear open- 

 ing as large as orbit, without marginal serrations. Scales of body 

 small, slightly imbricate, homogeneous, smooth, in transverse series, 

 and obliquely longitudinal, larger on rump, smaller on the sides; a 

 slightly larger vertebral series forming a barely noticeable dorsal 

 crest which extends from the nape to the beginning of the sacrum. 

 Abdominals smooth and equal; gulars a little smaller, equal on plica. 

 A prebranchial and postbranchial fold. Scales of fore limbs moder- 

 ate, some of those on femur and tibia much larger, spiniferous. Tail 

 short, flat, and covered with 15-25 whorls of strong, erect, conic, 

 spinous scales, which are not separated by smaller flat scales. The 

 scales below are margined and keeled, the carina being prolonged into 

 a flat spine. Spiniferous superior whorls made up of seven longitu- 

 dinal series; the spines being erect, those of the median row smaller. 

 With hind limbs extended the longest digit does not reach the axilla. 

 Femoral pores 6-6 to 11-11. 



Measurements. — m.c.z. no. 7095, 



adult, male 



Length of head 32 mm. 



Length of body 90 mm. 



Length of tail 100 mm. 



Total length 222 mm. 



Width of head over orbits 17 mm. 



Coloration. — General color, bright olivaceous. Shoulders and inter- 

 scapular region almost black; the latter with two cross series of green 

 spots, more or less distinct on the whole body in young specimens. 

 88910—28 4 



