1904.] IN" LIZARDS OI^ THE GENUS TILIQUA, 157 



in the British Museum,' Mr. Boulenger uses as part of his 

 definition of the Scinciclse* the sentence " Ossified ahdominal ribs 

 are absent " ; and in defining the Anel_y'ti'opida3 f he includes in 

 that definition the phrase " Abdominal ribs present."' It is not 

 absolutely clear from the wording used whether these two nearly 

 related famihes are to be distinguished ((inter alia) by the absence 

 or presence of " abdominal ribs" {i. e., as already pointed out, the 

 ventral moieties of post-stei-nal i-ibs) or by the mere absence or 

 presence of ossification in such ribs. In any case, not only lias 

 Peters figured complete hoops in Acontias. but I have Ijeen able 



Text-fig. 30. 



TiUqili' xcijico/des. 



Veutral Hap of musculature (B) in which lie the abdominal ribs, turned down to 

 show the deeper-lj'ing muscles (C), in which are imbedded the true ribs (D). 



to show in the present communication that considei-able Aestiges 

 of the venti-al moieties of post-sternal ribs occur in Tiligua. 



It is to my mind possibly a matter for further enquiry fis to 

 how far the median venti-al region of the post-sternal idbs which 

 actually meet each other behind the sternum may not he actually 

 a parasternum fused with true i-ibs. Foi' the median region of 

 the chevrons, whether of undoubted abdominal ribs or of true 

 vertebral ribs, appears at the surface of the abdominal musculature. 

 This median region, therefore, at least of the post-sternal true 

 ribs may conceivably be a vestige of a parasternum in those 

 Lacertilia where such ribs occiu-. 



* Vol. iii. p. 130. t Vol. iii. p. 430. 



