269 



DEGEXEEATION IN THE LIMBS OT SOUTH AFIUCAX 

 SEEPEXTIEOIiM LIZx\EDS (CHAMAESAUEA). 



BY 



J. E. DuERDEN, M.Sc, Ph.D., 



Professor of Zoology, Rhodes University College, 



AXD 



E. Essex, B.Sc. 



With 4 Text Figures. 



Read July 11, 1932. 



The South African genus of lizards, Cliainaesaura, comprises 

 three species, in each of which the limbs are greatly reduced and 

 the body is snake-like in form, due to an elongation of the tail 

 region. The limb degeneration has proceeded to a different degree 

 in each of the species. Thus in C. aenea both pairs of limbs are 

 present, but are greatly reduced in size in comparison with 

 ordinary lizards, and the normal five-clawed digits occur; in ('. 

 anguina both pairs are also present, but are styliform and barely 

 divided into two minutely clawed digits; while in C. macrolepis 

 the fore-limbs are altogether absent, and the hind-limbs are styli- 

 form and undivided. In all three the limbs lie closely appressed 

 to the sides and, with the possible exception of C. aenva, are 

 manifestly too weak to be of much service in progression. The 

 purpose of the present investigation is to determine the method 

 according to which the degeneration of the limbs has taken place, 

 as possibly throwing some light upon the manner in which retro- 

 gressive evolution proceeds. 



We are under obligation for specimens to Mr. J. Hewitt, 

 B.A., Director of the Albany Museum; Dr. E. Warren, Director 

 of the Pietermaritzburg Museimi ; Mr. C. J. Swierstra, Director 

 of the Pretoria Museum ; and Mr. F. W. FitziSimons, Director of 

 the Museum, Port Elizabeth. 



The method pursued in each case has been to macerate the 

 specimens for a time, either in water or in weak caustic potash, 

 and then to remove the limbs. By careful manipulation under 

 the dissecting microscope it was possible to dissect away the 

 covering of lanceolate keeled scales and the greater part of the 

 underlying inuscle, clearing afterwards in a mixture of glycerine 

 and alcohol. Some of the limbs have been stained in picric acid, 

 after dissection, cleared in xylol and permanently mounted. 



Chamaesaura aenea. 



In this species the two pairs of limbs have merely undergone 

 reduction in size, without the loss of any of the constituent parts,. 

 From their > attachment to the body to the tip of the longest 

 digit, the fore-limbs vary in length from 9 to 11 mm. and the 



