THE SACRUM OF THE LACERTILIA. 



ROY L. MOODIE, 

 The University of Chicago. 



The question of the morphology of the transverse processes 

 of the sacral vertebrae of the Lacertilia seems never to have 

 been definitely settled. There are extremely diverse statements 

 in our various works on zoology concerning the exact nature of 

 these processes. So far as I have been able to determine no one 

 has ever taken up the study of the young stages of the lizards 

 in order to determine this point. At the suggestion of Dr. S. 

 W. Williston I have undertaken such a study while engaged in 

 clearing the young and adult stages of a number of reptiles in 

 the course of an extensive investigation on the epiphyses of the 

 Reptilia. 



The problem as it presents itself is whether or not the Lacer- 

 tilia possess sacral ribs. If they do, there should be separate 

 centers of ossification for these elements and we may confidently 

 expect to find them in the embryonic condition. If there are no 

 ribs, there should be no separate centers of ossification nor would 

 sutures of separation of the ribs from the centra persist in the 

 young of the lizards. The question as to whether the lizards 

 ever had sacral ribs is not fully discussed. If the forerunners of 

 the lizards had such ribs there would probably be a cartilaginous 

 remnant of them in the embryo. 



The material investigated includes the young and adult stages 

 of representatives of five families of the Lacertilia, viz. : (i) Cham- 

 eleonidae — Chameleon owenii Grey, two specimens, one young 

 and one adult from Batanga, German East Africa. (2) Iguan- 

 idse — Iguana sp. ?, one young specimen from Mexico. PJiryno- 

 sonia douglassi Jiernandesi Girard, three specimens, two young 

 and one adult, taken in Natrona Co., Wyoming, this past summer 

 by the writer. Sceloporus sp. ?, one young specimen from Mexico. 

 Sceloporus chrysosticus Cope, nine specimens, eight young and one 

 adult from Zopopan near Jalisco, Mexico on the semi-arid upland 



