18 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 73 



Pedro, Santa Anita, San Antonio, San Bartolo, Buena Vista, Santi- 

 ago, Agua Caliente, Sierra San Lozaro, Pescadero, Trumfo, Todos 

 Santos, and Hanson Laguna. It has also been taken on the follow- 

 ing islands in the Gulf of California: Geralbo, San Esteban, and San 

 Pedro Nolasco. 



The questionable occurrence of this species on the mainland of 

 Mexico is mentioned below under the remarks on the species. 



Van Denburgh, who in all probability examined and studied more 

 individuals of this species than any other worker, published in 1922^* 

 the most accurate account concerning it. From this paper I have 

 quoted freely, placing in quotation marks the extracts taken there- 

 from. The description which follows immediately has been slightly 

 modified according to my observations. 



Description. — U.S.N. M. No. 69489-H, grown cotype; M. C. Z. 

 No. 13179, adult male; 3178, adult male; A. M. N. H. No. 2073, adult 

 male. Body considerably compressed. Tail conical at base, where 

 almost square in sections. Limbs and head large, latter sharply tri- 

 angular with flattened top and almost vertical sides. Nostrils large, 

 in a round plate whose posterior edge is nearer to orbit than to end 

 of snout. Rostral and symphyseal plates very broad and low. Ten 

 labials. A very large plate below the eyes; a series of large super- 

 ciliaries. Entire top and sides of head covered with small, irregular 

 hexagonal plates, convex, except on snout and lores. Ear opening 

 very large, almost vertical, and without denticulation. Several series 

 of large sublabial plates, passing gradually into gulars. Dorsal crest 

 begins some distance behind shielded part of head, is composed of 

 high spines on nape, and gradually diminishes in height posteriorly. 

 It is continued on middle third of vertebral line of body as a series 

 of enlarged flat plates, but is not traceable on posterior third. Back 

 and sides covered with small, smooth, subquadrate scales, which pass 

 gradually into larger ventrals. Gular region covered with smooth 

 scales, which become gradually larger posteriorly. Smallest gulars 

 larger than dorsals, the largest smaller than ventrals. Scales on 

 limbs all smooth. Tail bearing whorls of spinous scales; the first 

 and second, and occasionally the third, of these whorls separated from 

 each other by three series of smaller smooth scales; third, fourth, 

 fifth, and sixth spiny whorls each preceded by two series of smooth 

 scales, and the more distal whorls by single series which gradually 

 become spinous. Number of femoral pores ranges from four to eight 

 on each side. Dorsal crest higher in males than in females, but 

 never continued on posterior part of back. 



» Van Denburgh. Occ. Papers of California Acad, of Sci., No. 10. The Kept, of W. N. Amer., Part 1, 

 Lizards, pp. 67-71, 1922. 



