298 .4^'^^lL^• yi:w yonk academy of sciences 



part oi the modern Soutli American fresh-water fish famia is derived 

 from North America ; but how he reconciles this with the recorded pres- 

 ence of several of the most typical genera in the Green Eiver Eocene of 

 Wyoming, I do not see. 



A few cases in point may be noted, as follows : 



Lepidosteiis, now Central American and southern Sonoran. Al)undant 

 in all the Eocene formations of the northwestern States, as also in Europe. 



Pliractocephalus. Arins, etc., now South American, nearly related to 

 Rhineastes of the Bridger and Amyzon beds of the western States. 



Osteoglossus of Brazil, Borneo and New Zealand, Vastres and Tletero- 

 tis, also southern types, closely related to Dapedoglossus of the Green 

 Eiver shales (Eocene). 



The characins, which form so important an element of the modern 

 South American fauna, are, as Eigenmanu holds, largely a local expan- 

 sive radiation conditioned by the immense ramifying river-systems of 

 that continent. But, considered in their more general relations, they are 

 a primitive group, the northern cyprinids being a higher and later de- 

 velopment. 



The catfish, which in the North have the characteristics of a disappear- 

 ing group, are numerous and dominant in South America. Eigenmann 

 calls attention to the paucity of the Patagonian fauna and its apparent 

 relations to that of New Zealand and Australia (Galaxiids and Ap- 

 lochitonida?). He does not, however, attach any great weight to this as 

 evidence for a former Antarctic connection, regarding it as "highly theo- 

 retical and precarious" so far as the fresh- water fish are concerned — but 

 "The evidence from other sources of a former land connection has be- 

 come conclusive." I might observe here that many students in other 

 groups are equally doubtful of the conclusiveness of the evidence for 

 Antarctic connections in the groups with which they are familiar, while 

 equally ready to accept as conclusive the evidence in groups with which 

 they are not I'amiliar. 



As regards a connection of tropical Africa with tropical South Amer- 

 ica, Eigenmann is much more positive, basing it mainly upon tlio chara- 

 cins and cichlids, common to both continents. There is no species or 

 genus common to the two continents. Both J'amilies are relatively primi- 

 tive, as compared with northern related groups. As regards their former 

 presence in the northern world (which Eigenmann does not allude to) or 

 their parallel adaptation from marine forms of Cretaceous or early Ter- 

 tiary time, there is little satisfactory evidence. Nevertheless, the fact 

 that they represent an adaptive divergence from an intermediate and 

 more primitive type ancestral to carp and catfisli is a suggestive one. 



