?> 



698 DE. c. I. FOESi"TH MAJOR ON THE [June 1, 



preceding species. The anterior one in upper, the posterior 

 one in lower molars being divided in the middle of the crown at 

 an early stage of wear, the pattern presented in middle-aged 

 specimens is the following : — a single enamel loop opening on the 

 inner side of upper and on the outer side of lower molars ; two on 

 the outer side of upper and the inner side of lower molars. The 

 single loops on the inner side of upper and on the outer side 

 of Jower molars remain open for a longer time than the others. 

 Dimensions in millimetres, taken in the flesh : — 



Skin 

 (M.516),2. 

 Type. 

 Length of head and body 142 



tail 89 



manus 12 



pes 28 



,, ear 17*5 



Breadth of ear — 



Loc. Ampitambe, outside the forest. Viuanitelo, close to the 

 forest of the Independent Tanala of Ikongo, thirty miles south of 

 rianarantsoa. The specimens measured are from the former 

 locaUty. Fossil in the Children's Cave near Sirabe ; abundant in 

 the superficial, very rare in the lower deposits. 



The Affinities of the Genus Brachyuromys with Tachyoryctes, 

 B,hizomys, Spalax, and Siphneus. 



1. Tachyoryctes and Rhizomys. — With regard to the affinities of 

 Brachyuromys, I made on a former occasion ' the following state- 

 ment : — " The African and Asiatic Ehizomyes, usually classed in the 

 Spalacidce, but which Winge places amongst the lowest Muridce, 

 alongside with the Tertiary Cricetodon and Eomys, are nearly related 

 to the Malagasy group of Eodents by means of the Abyssinian 

 Tachyoryctes {Rhizomys) and the Malagasy i?/'rtc7;?/it/-o«(?/s, the former 

 being but a very specialized fossorial form of the more generalized 

 Brachyuromys ramirohi.tra. The molars are almost identical in 

 both, only slightly more hypsodont in Tachyoryctes." (They are 

 much more so in the latter than in the former.) " If we divest 

 the Tacltyoryctes skull of its [excessive] fossorial characters and of 

 the consequences of the more hypselodont molars, we obtain a 

 Brachyuromys skull. Likewise the skulls of the young Tachyo- 

 ryctes bear much greater resemblance to Brachyuromys than the 

 adult. There is further a great correspondence in external 

 characters if we disregard the smaller ears and eyes of 'Tachyo- 

 ryctes and its fossorial claws." 



In the following 1 give the reasons for the above statements. 



In spite of all the differences of the skulls at first sight, a closer 



I P. Z. S. 1896, p. 'J71>. 



