178 On Megaladapis madagascariensis. [June 



Lemurids, and probably most of all to Chirogaleus. These rese 

 blances would consist in a more rounded cerebral cranium, in 

 brain-cavity being relatively much more voluminous, and possi 

 even absolutely so, than in aged specimens, and the facial porti 

 more shortened. Especially it is to be expected that the p 

 orbital elongation of the frontals, an isolated feature in t 

 Lemuroidea, will be absent in young specimens, as it is due solely 

 the development in the adult of aerial sinuses. 



Passing to considerations of a more general nature, it is strongly 

 be insisted upon, as one of the results of this investigation, that t 

 short cerebral and elongated facial portion of the cranium, universa 

 accepted as a characteristic feature of the primitive Mammalian sku 

 are, on the contrary, indicative of a very specialised condition. 



The author maintains that retrogressive evolution is more f 

 quently to be met with amongst the Mammalia than has hitherto 

 admitted, " low " organisation being by no means always synonym 

 with " primitive " organisation. 



In accordance with the conclusions arrived at, the author sugge 

 the establishment of a new genus, Megaladapis, for the present fossil 

 skull, as well as its collocation in a distinct family of the Lemuroidea. 



"1. Adapidae, Adapis (extinct). 



2. Anaptomorphidae, Anaptomorphus, Necrolemur 



(extinct.) 



Lemuroidea ^ 3. Lemuridae (recent). 



I 1 4. Megaladapidae, Megaladapis (extinct). 



5. Chiromyidae (recent). 



U>. Tarsiidae (recent). 



As bearing upon the question of the geological age of Megaladapis, 

 the author briefly reviews the contemporary Yertebrate fauna which 

 has been brought to light by the explorations of Mr. Last, and the 

 earlier researches of Grandidier, who (26 years ago) explored the 

 same marsh at Ambolisatra. Some of the Mammalian remains 

 obtained are too scanty to admit of accurate determination, but they 

 are sufficient to indicate other not less strange members of this 

 curious fauna. The following Yertebrata may be enumerated : 



MAMMALIA : Megaladapis madagascariensis, Major. 



Hippopotamus Lemerlei, Grand. 



Potamochcerus, sp. 

 AYES : JEpyornis maximus, Is. Geoff. St. Hilaire. 



medius, Milne-Edw. and Grand. 



modestus, Miliie-Edw. and Grand. 

 EMYDOSAURIA : Crocodilus rolustus, Grand, and Yaillant. 

 CHELONIA : Testudo Grandidieri, Yaillant. 

 dbrupta^ Grandidier. 





