TEIID LIZATJDS OF THE GENUS CNEMIDOPHORUS 211 



Also, a i'lirdicr clalxtralioii oi" the iclal ioiisliips of {\\v>v li/ards will 

 be found in the suniiiuuT of the tesseliatus group ([). 221). 



CNEMIDOPHORUS BACATUS Van Denburgh and Slevin 



SAN PEDRO NOLASCO ISLAND SPOTTED WHIPTAIL 



1921. Ciwmidophonis bacatiis Van Dknuukgii and Slevin, I'l-oc. Calif. Acad. 

 Sci., ser. 4, vol. 11, p. 97 (type locality, "San Pedro Nolasco Island, Gulf of 

 California, Mexico"; typo specimen, C.A.S. No. 49152, J. R. Slevin, collector). 

 —Van Denbukgh, Occas. Pap. Calif. Acad. Sci., vol. 10, 1922, p. 544. — 

 Schmidt, Bull. Amer. Mus. Nat. Hist., vol. 46, 1922, p. G25.— Stejneger and 

 Bakbour, Check List N.A. Ampli. and Kept., ed. 2, 1923, p. 70. — Sclater, 

 Zool. Rec. for 1922, vol. 59, "Reptilia," 1924, p. 23. 



Systematic notes. — Bacatus and catalinensls are apparently very 

 closely related in spite of their splendid geographical isolation from 

 each other, for they represent the same end development of the 

 color pattern of the tessellatus group. It is only because of the 

 apparent constanc}^ of their distinctive characteristics and the wide 

 separation of their respective habitats that the two forms are given 

 full specific rank here. 



Diagnosis. — The distinctive features of the form are all colora- 

 tional. Bacatus may be separated from the very closely allied cata- 

 linensls by the possession of fewer, more distinct, dorsal spots, which 

 are white, rather than yellowish. Furthermore, in the region above 

 the level of the tympanum and anterior to the insertion of the 

 forearm, there are no spots or indications of spots, such as are 

 present in catalinensis. There are no indications of longitudinal 

 stripes, crossbars, or recticulations in either species, such as those 

 that occur in martyrls^ canus, and tessellatus. 



Bacatus is distinguishable from all other spotted Cnemidophori 

 (except catalinensis) by its small adult size. 



Descriftion. — Snout rather blunt ; nostril anterior to nasal suture ; 

 anterior nasal usually not in contact with second upper labial; 

 supraoculars 4; supraocular granules extending forward to the 

 middle of the third supraocular ; frontoparietals 2 ; parietals 3 ; 

 occipitals small, irregular, largest anteriorly; anterior gulars mod- 

 erate, rather uniform, a few enlarged granules medially and medio- 

 laterally; posterior gulars small, uniform; mesoptychial scales mod- 

 crate, median largest, in 5-7 transverse row^s; post-mesoptycliial 

 granules on the edge of the collar fold. 



Body elongate; ventral plates in 8 longitudinal and 34—36 trans- 

 verse rows ; dorsal granules small ; limbs moderately long, well de- 

 veloped; brachials -4-0; antebracliials 2-3; brachials and antebrachials 

 more or less continuous at a point of contact; postantebrachium with 

 a few enlarged granides; femorals G-8; tibials 3; femoral })()res 1(5- 

 21; tail elongate, tapering; caudal plates large, oblique, and with 

 rather strong lateral longitudinal keels. 



