1S92.] 185 jCope. 



The Osteology of the Lncertilia. 



By E. D. Cope. 



(Read before the American Philosophical Society, March IS, 1S92.) 



la the following pages is presented si review of the osteology of the 

 Lacertilia with especial reference to the genera represented in the Nearc- 

 tic fauna. It is based on the skeletons placed at my disposal by the 

 U. S. National Museum, the Academy of Natural Sciences, and those con- 

 tained in my private collectioo. It includes also the record of my 

 observations and notes made in the principal European museums twenty- 

 five years ago. The characters discovered by me at that time, which I 

 found to be of the greatest taxonomic importance, I enumerated in a paper 

 which is printed in the Proceedings of the Philadelphia Academy for 1864, 

 p. 224. The use then made of those characters has been generally 

 accepted by subsequent writers.* There are, however, many other char- 

 acters whose value is of uncertain taxonomic value, wliicli were not then 

 mentioned, and which I now record. 



The first description of the osteology of the Lacertilia is that of Cuvier, 

 which is contained inhis OssemensFossiles ; (Vol. x, ed. 1836). This is an 

 excellent one, but the many types discovered since his time render it nec- 

 essary that a new survey of the subject should be made. In 1856 the 

 Zootomie der Amphibien, by Stannius, appeared. The account of the 

 osteology of lizards given in this work is more complete than that of 

 Cuvier, but it is iucomplete in many points, and is not up to the re- 

 quirements of the present lime. The present study is made with especial 

 reference to the necessities of the paleontology of the order ; therefore the 

 description of characters is made as specific as possible. The principal 

 novelty will be found in the references to North American Genera, and in 

 the descriptions of the hyoid apparatus. The description of the scapular 

 and pelvic arches in certain genera with the extremities degenerate or 

 wanting, where they have not been previously described, is contained in 

 a separate illustrated paper now in the hands of the editor of the Ameri- 

 can Journal of Morphology for publication. 



Skull. — The premixillary bone is single except in the Scincidi^, Acon- 

 tiidse, and some Gecconidae (Phyllurus sp.). It is very small in the 

 Iguanid genus Phrynosoma, and in the AgamidiB it is excluded from con- 

 tact with the vomer by processes of the maxillaries which meet on the mid- 

 dle line. In the Chamajleouidtie the premaxillary is still smaller, the body 

 being narrower than the superior spine, and supporting but one tooth. In 

 the Aaguidie the premaxillary is bounded posteriorly on each side by a fora- 

 men which is sometimes large, which is wanting in other families, includ- 

 ing the Helodermidse. In Lepidosternum it is principally on the inferior 



* See Boulenger, Ann. Magaz. Nat. History, 1884, p. 117 ; and Catalogue of Lizards in 

 British Miiseam, i, 1883; ii, 1885; iii, 1887. Ttiis author has added osteological charac- 

 ters of the Eublepharidai, Uroplatidtc, Pygopodidie and Dibamidte. 



