216 ANNALS NEW YORK ACADEMY OF SCIENCES 



SECTION OF BIOLOGY. 



13 November, 1911. 



Section met at 8:l. r ) p. m., Vice-President Frederic A. Lucas presiding. 

 The minutes of the last meeting were read and approved. 

 Dr. Frederic A. Lucas was nominated, for Vice-President of the Acad- 

 emy and Chairman of the Section for 1912. 



Dr. W. K. Gregory wa s elected Secretary of the Section for 1912. 

 The following programme was then offered : 



W. K. Gregory, Further Notes on the Evolution of Paired Fins. 

 C. William Beebe, Notes on a Pheasant Expedition to Asia. 



Summary of Papers. 



Dr. Gregory said in abstract: The problem under consideration is a 

 phase of vertebrate phylogeny and should be studied in connection with 

 this larger problem. In very early acquiring myotomes, the ancestral 

 vertebrates gained a means of locomotion, by lateral flexures of the body, 

 that was more efficient than movement by means of ciliated epidermis. 

 The earliest vertebrates probably fed on microscopic particles obtained 

 by ciliary ingestion. The Upper Silurian Birkenia of Traquair ap- 

 parently had no biting jaws and may have sucked in small food particles, 

 like the larval lamprey. Well-preserved material showed that none of 

 the Ostracoderms had cartilage jaws or teeth, but the dermal plaques 

 around the oral hood sometimes functioned as jaws. Typically carniv- 

 orous habits, involving true cartilage jaws, true teeth and both paired 

 and median fins, are first known in the Acanthodian sharks, of the 

 Upper Silurian and Devonian. In brief, fins of all kinds, conditioned in 

 their first appearance by the presence of myotomes, were evolved as an 

 incident in the general transformation of acraniate minute forms, with 

 ciliary ingestion, into well-cephalized fishes of carnivorous habits. The 

 speaker reviewed the evidence for the "fin-fold" theory in the different 

 groups and stated some apparently new objections to the "gill arch" 

 theory. He cited evidence tending to show that the various paddle-like 

 types of paired fins with widely protruded basal cartilages had evolved 

 from fin folds independently in the sharks, Crossopterygians and 

 Dipnoans. 



The paper was illustrated with lantern slides. 



Mr. Beebe gave a short talk, illustrated with lantern slides, on the 

 recent trip which he and Mrs. Beebe made around the world in search of 



