144 



DE. n. r. STANDING ON SUBF0S8IL 



Table 25. — Giving dimensions (in millimetres) 



Maxim um length of os innominatum 



From summit of ilium to superior edge of 

 acetabulum 



Maximum diameter of acetabulum 



Minimum diameter of body of ilium (above 

 acetabulum) 



Breadth of ilium at level of iliac spine 



Width of sacral surface 



Distance from pubic suture to ischial 

 tuberosity 



briefly a considerable number of the characters enumerated by various writers as 

 differentiating the " Lemuroidea " from the " Anthropoidea." 



Several preliminary observations should, however, be made before entering on this 

 comparative survey : — 



(1) It should be clearly realised that all the subfossil Lemuroids hitherto described 

 although extinct are of very recent date, and from the biological and geological points 

 of view are the contemporaries of the existing genera. 



(2) In considering the characters of a group of animals, especially where marked 

 specialisation and retrogression have occurred, it will not always be possible to 

 distinguish between ancestral and acquired characters. 



(3) When any doubt exists we are on the whole more likely to be correct when we 

 interpret as vestigial r?ii\iQx than as recently acquired any suggestions of Simian affinity *. 



(4) It is in regard to brain-development and such structures as depend upon brain- 

 development that we are likely to find the least satisfactory evidence as to close actual 

 affinity with the higher Primates ; but, on the other hand, it is here that we shall find 

 the clearest evidence of degeneration. 



(5) Where all the Malagasy genera agree in possessing in various degrees some 

 character which would ordinarily be described as " Lemuroid," it may be often possible 



* it should be noted that it is some of the extinct genera of Lemuroids which show the greatest number 

 of "Anthropoid " characters ; and it would seem more reasonable to regard these features as ancestral than 

 to consider them as adaptive modifications which have arisen by convergence in Madagascar. Wo have seen, 

 on the other hand, that the specialisation in certain directions to which apparently the recent Lemurs owe 

 their survival («. jf. the procumbent i^ectinate disposition of the lower incisors) is just such as has tended 

 to disguise their close relationship to the Simian type. 



