508 



SCIENCE 



[N. S. Vol. XXXIII. No. 



dine whale," is referable to Balanoptera arctica 

 Schlegel, and although it has been taken for 

 a number of years at the Japanese stations almost 

 no material relating to it is extant. The species is 

 so closely allied to Balosnoptera borealis Lesson of 

 the Atlantic that further investigation will prob- 

 ably prove it synonymous. 



Photographs of the rare North Pacific blackfish 

 (Globicephalus scammoni) and of several species 

 of dolphins were also shown. It was announced 

 that a new porpoise of a most peculiar body 

 shape had been secured, and would be described 

 in a future number of the American Museum 



At the regular meeting of the section held at 

 the American Museum of Natural History, Feb- 

 ruary 13, 1911, Chairman Frederic A. Lucas pre- 

 siding, the following papers were read: 

 Climate and Evolution: W. D. Matthew. 



The thesis of the paper is as follows: 



1. Secular climatic change has been an impor- 

 tant factor in the evolution of land vertebrates 

 and the principal known cause of their present 

 distribution. 



2. The principal lines of migration in later geo- 

 logical epochs have been radial from holarctio 

 centers of dispersal. 



3. The geographic changes required to explain 

 the past and present distribution of land verte- 

 brates are not extensive and do not affect the 

 permanence of the ocean basins as defined by the 

 continental shelf. 



4. The theory of alternations of moist and uni- 

 form with arid and zonal climates associated, re- 

 spectively, with partial submergence and extreme 

 emergence of the continental areas, as elaborated 

 by Chamberlin, are in exact accord with the ap- 

 parent course of evolution of land vertebrates, 

 when interpreted with due allowance for the prob- 

 able gaps in the geologic record. 



5. The numerous hypothetic land bridges in 

 temperate, tropical and southern regions, connect 

 ing continents now separated by deep oceans 

 which have been advocated by various authors 

 are improbable, inconsistent and unnecessary to 

 explain geographic distribution. On the contrary, 

 the known facts point distinctly to the perma 

 nency of the deep-ocean basins during the later 

 epochs of geologic time, to the alternate connec- 

 tion and separation of the land areas within the 

 Ime of the continental shelf and to the continued 

 isolation of those land areas which are surrounded 

 by deep ocean. 



These theories are substantially an adaptation 

 of the conservative views of Wallace and other 

 zoologists to the geological theories of Chamberlin. 

 They are defended by a consideration (1) of the 

 nature and extent of the defects in the geological 

 record; (2) of the relations of the zoological re- 

 gions to each other and the changes effected by 

 elevation or submergence of 100 fathoms; (3) of 

 the principles of dispersal of land animals; (4) of 

 the character of the fauna of oceanic islands (in- 

 cluding Madagascar, Cuba and New Zealand) and 

 the degree of probability which attaches to acci- 

 dental transportation as a means of populating 

 them; (5) of the present and known past distribu- 

 tion of the mammalia, group by group, in consid- 

 erable detail; (6) of the distribution of the dif- 

 ferent orders of reptilia in a less detaOed manner; 

 (7) of the distribution of birds and fishes, with a 

 few instances from invertebrate distribution which 

 have been especially urged in support of hypo- 

 thetical bridges; (8) of the objections to such 

 bridges and an interpretation of the real signifi- 

 cance of such evidence as has been adduced in 

 support of them. 



The speaker believed that the supposed cumu- 

 lative evidence obtained in various groups of ani- 

 mals or plants for various continental bridges is 

 due simply to identical errors in interpretation 

 running through all such instances. On the other 

 hand, to admit such bridges would seem to involve 

 certain distribution results, which, in the groups 

 which he has studied, assuredly do not exist. 

 The Limhs of Eryops and the Origin of Paired 



Limhs from Fins: W. K. Gkegort. 



In a skeleton of the temnospondylous amphib- 

 ian, Eryops megacephalus Cope, from the Permian 

 of Texas, which is now being mounted in the 

 American Museum, the limbs are of special inter- 

 est. Many resemblances to the contemporary rep- 

 tile Diadectes are seen: in the stout, long coraco- 

 scapula, the short, wide-headed humerus, with its 

 very wide, prominent and backwardly directed en- 

 tocondyle, in the short fore-arm, in the very heavy, 

 solid pelvis, stout femur and fully ossified carpus 

 and tarsus. In the character of its limbs Eryops 

 was on the whole nearer to Sphenodon than to the 

 Urodeles, though far more archaic than the former. 

 As shown by the facets, the humerus and femur 

 were held almost at right angles to the body, the 

 opposite feet being held very widely apart. 



The generalized character of the limbs of 

 Eryops with respect to those of higher Tetrapoda 

 invite renewed inquiry into the origin of paired 

 limbs from fins. The limbs of known branchio- 



