TITLES AND ABSTRACTS OF PAPERS 221 



the three primary arms: later an additional dei)ression is found on the dextral 

 side of each arm. Each depression is connected with the food-groove system 

 by a pore passing between two or three of the marginal plates of the tegmen. 

 At first, the depressions show no evidence of articulation with anything. 

 Later, as they grow in size, the articulating ridge mentioned in the preceding 

 paragraph makes its appearance. Still later, articulating surfaces for the 

 attachment of full-sized arms are found where younger specimens show only 

 depressions, but in the meantime additional small depressions appear along 

 some of the neighboring sutures between the more or less marginal plates of 

 the tegmen, and the latter, in time, also developing articulating ridges and 

 then articulating surfaces, until 14 or more articulating surfaces for full- 

 sized arms are present. 



In this process it is probable that well developed arms with biserially ar- 

 ranged plates were accompanied by much smaller arms with plates in their 

 xnore initial stages ; and the still younger arms, at their first appearance ex- 

 terior to the theca, may have been free from protective plates altogether. 



Since even the largest and most mature specimens of Caryocrinites show 

 depressions in addition to the articulating surfaces for fully developed arms, 

 it is possible that some of the later developed arms functioned genitally and' 

 did not serve merely for the conveyance of food. 



The argument for the recognition of the Paleocene as a distinct epochv 

 of the Tertiar}' was presented briefly by the author. 



STATUS AXD LIMITS OF THE PALEOCENE 

 BY W. D. MATTHEW 



(Abstract) 



The term Paleocene has been revived by several vertebrate paleontologists^ 

 in recent years to cover the faunal zones previously known as Basal Eocene. 

 Upon evidence of the vertebrate faunas it is entitled to rank as a distiiict 

 epoch, coordinate with the Eocene and Oligocene. It includes the Puerco, 

 Torrejon, Fort Union, and probably certain less known vertebrate faunas in 

 this country, and the Cernaysian in France. Its upper limit is marked by the 

 first appearance of the principal modern orders of mammals and of certain 

 modern groups of reptiles simultaneously in Western America and in Western 

 Europe. The lower limit is more doubtfully fixed by the first appearance of 

 placental mammals. The evidence of marine invertebrates and of plants does 

 not at present appear to support the distinction of the Paleocene as a separate 

 ep)och. It is possible, however, that it covers the gap between the Cretaceous 

 and Tertiary insisted upon by many stratigraphers and paleobotanists, and 

 there are other possible interpretations that might reconcile the evidence. 

 The writer believes that the epoch may also prove to include the Lance and 

 certain other dinosaur-bearing formations, and that it may belong rather to^ 

 the Cretaceous than to the Tertiary period. No final conclusions are in order 

 until the evidence in different fields has been satisfactorily reconciled. 



