AKT. 12 REVISION OF LIZARDS OF GENUS CTENOSAURA — BAILEY H 



Diagnosis. — A conspicuous transverse gular fold; median dorsal 

 scales 65-80, considerably larger than body scales forming a serrated 

 €rest of slight elevation extending from the beginning of the neck to 

 the sacrum; dorsal crest not even indicated by a row of carinated 

 scales in sacral region. Tail very long and strongly marked into 

 numerous verticilli (whorls or rings) , composed of very long and very 

 strongly carinated scales, each terminating in a lengthened point, 

 thereby causing a spiny appearance throughout entire length of tail; 

 whorls of spinous scales separated from each other by rows of smaller 

 flat scales; first and second or first, second, and third whorls separated 

 by three rows of smaller flat scales; next five or six whorls separated 

 by two rows of smaller flat scales; a few whorls separated by one row 

 of flat scales, these flat scales gradually becoming spinous until at or 

 near middle of tail small flat scales disappear and tail exhibits a spiny 

 appearance to end. (Of course a broken tail that has been regener- 

 ated does not possess the armed scales on the regenerated portion.) 



Distribution. — 'This ctenosaur has the widest distribution of any 

 member of the genus. It ranges from the States of Sonora and 

 Chihuahua, Mexico, southward to the Isthmus of Tehuantepec, 

 inhabiting sandy beaches and the foothills of the various mountain 

 ranges. Most of the specimens that have been collected have been 

 taken on the coastal slopes of the mountain ranges, very few being 

 recorded from the interior regions. Specimens taken on the islands 

 in the Gulf of California and at Cape St. Lucas, Lower California, 

 were in all probability carried over from the mainland. These lizards 

 are regarded as food by some Indians and are often carried alive 

 from place to place for that purpose. 



Many specimens in the museums in this country and in Europe 

 bear simply the locality label "Mexico." However, enough properly 

 labeled material has been examined to insure accurate distribution 

 charts. Specimens have been taken at Batopilas, Chihuahua, Mex- 

 ico; on the western foothills of the Sierra Tarahumare Mountains; 

 Tampico and Manuel, Tamaulipas; Miramar, Cerro del Gallo, 

 Jalapa, and Panuco, Vera Cruz; Escuinapa and Tres Marias Island, 

 Na3^arit; Uruapan, Michoacan; Tlopa, Guerrero; Tetela, Morelos; 

 Tehuantepec, Dominguillo (Domingville) ; and Cuicatlan, Oaxaca. 



Description. — Brit. Mus. Nat. Hist. 20a. H. grown female type; 

 Berlin No. 577, H. grown male now M. C. Z. No. 22453, cotype of 

 cycluroides; M. C. Z. No. 16070 adult male. Head elongate, fiat 

 above, covered with somewhat small hexagonal scales, and very dis- 

 tinctly marked off, as it were, from body; muzzle narrowed, covered 

 with rather large smooth scales; supraoculars small, flat, and hexag- 

 onal, externals only about one-half as large as internals, and separated 

 from each other by three rows of scales; ear opening almost as large as 

 orbit; no dewlap; transverse gular fold present; parietal scales slightly 



