﻿270 ALLEN S NATURALISTS LIBRARY. 



The type species of the genus, several others having been 

 named. 



DistrilDiition. — Tertiary formation of Patagonia. 



Before quitting these interesting, but still very imperfectly 

 known, extinct Patagonian Marsupials, a few words may be 

 added as to their importance from a distributional point of 

 view assuming that (as appears to be justified by the number 

 of their incisor teeth) they are rightly regarded as allied to 

 the Dasyu7'idcE. In the first place, it may be mentioned 

 that it has long been a matter of common knowledge that 

 there exist certain very remarkable relationships between the 

 fauna and flora of all the great southern continents. For 

 instance, among Mammals, the rodent family Ododontidce. is 

 peculiar to South (including Central) America and Africa, in- 

 cluding Algeria. Then, again, among fishes, the family of the 

 ChromidcB is confined to the rivers of South America and Africa, 

 with one outlying genus in India ; while the True Mud-fishes 

 {Lepidosh'e?! and Protopte7'us) are solely South American and 

 Ethiopian, the third representative of the same family being 

 the Baramunda {Ce7'atodus) of Queensland. Again, the 

 connection between the flora of Africa and that of Western 

 Australia is so intimate as to have induced Mr. Wallace to 

 express his belief that there must have been some kind of 

 land connection, although not necessarily a continuous one, 

 between these two widely distant areas. The connection 

 between the fauna of India and that of Ethiopian Africa is 

 now too well known to stand in need of comment. The 

 matter does not, however, end here ; for if we go back to 

 the Secondary epoch there are equally striking evidences of 

 the connection between the animals and plants of the southern 

 continents. For instance, an extinct Saurian genus known as 

 Mesoste?'num, which appears to have been allied to the Plesio- 

 saurs of the Lias, is known from early Secondary strata in 



