584 . abstracts: zoology 



ZOOLOGY. — A phylogenetic study of the recent crinoids, with special 

 reference to the question of specilization through the partial or com- 

 plete suppression of structural characters. Austin H. Clark. 

 Smithsonian Miscellaneous Collections, 65^'' : 1-67. August 19,1915. 

 A detailed analysis of the structure of the recent crinoids and a 

 comparison with fossil types indicates that phylogenetical advance has 

 been through a progressive simplification of the organism, evidenced 

 by a reduction in the number of the component parts. The pairs of 

 contrasted characters employed in differentiating the recent crinoids 

 are given, the more generalized of each pair being numbered 1 and the 

 more specialized 2, and the types falling under each are listed. By 

 simple addition this gives a numerical basis for the determination of 

 the phylogenetical status of all the recent types. Taking the most 

 primitive family (Plicatocrinidse) as 1 we find the families to be spe- 

 cialized, in terms of this family, as follows: 



Holopodidse 3.12 or 2.59 



Pentacrinitidse 2.79 or 2.19 



Bourgueticrinidse 2.48 or 2.13 



Apiocrinidae 1 .87 or 1 .67 



Phrynocrinida3 1 .74 or 1 .55 



Plicatocrinidse 1 .00 or 1 .00 



Thus the families according to their specilization fall into three 

 groups: (1) Holopodidse, Pentacrinitidse and Bourgueticrinidse; (2) 

 Apoicrinidae and Phrynocrinidse ; and (3) Plicatocrinidse. 



Of the individual structures which collectively make up the crinoid 

 whole the sequence in specialization is: (1) The skeleton as a whole 

 (most specialized); (2) calyx; (3) disk; (4) arms; (5) column; (6) 

 pinnules. 



On the basis of a broad average the more specialized characters 

 occur in shallower and warmer water than the more primitive. 



A. H. C. 



ZOOLOGY. — The distribution of the recent crinoids on the coasts of 

 Australia. Austin H. Clark. Internationale Revue der gesam- 

 ten Hydrobiologie und Hydrographie, 1915, pp. 222-234. 1915. 

 Australian crinoids fall into three groups, (1) Tropical Austral- 

 ian types, (2) South Australian types, and (3) East Indian types. 

 The distribution of each of these groups on the Australian coasts is 

 treated in great detail. A. H. C. 



