REPORT OK EXECUTIVE COMMITTER. 1 37 



problem of sexual selection. The forms used most extensively were 

 Pkilosamia cyant/iia and Rofh^childia jortilla, a Mexican species, 

 additional data being obtained from Hypenhiria io, H. budlcyi, Roths- 

 childia Orizaba, and Saniia ruber. Studies upon the course of in- 

 heritance in these species have also been prosecuted, the second 

 and third generations being obtained in some cases. Owing to 

 the peculiar nature of the material, it is impossible to present an 

 extended report upon the results obtained at the present time. 



J. E. Duerden, University of Michigan, Ann Arbor, Mich. Grant 

 No. 158. For continnatioii of investigation on the mo7-pJioIogy and 

 development of reeent and fossil corals. ^i , 500. 



Abstract of Report — Fossil Corals. — Investigations have been carried 

 out upon a large series of palaeozoic fossil corals obtained last year 

 from various collections at home and abroad. The studies, conducted 

 along developmental lines, have demonstrated conclusively (i) that 

 the primarj' stage of the rugose coral is hexameral, in contrast to the 

 tetrameral, which hitherto has been usuallj^ assumed ; (2) that the 

 later septa are added in a definite sequence within only four of 

 the six primary chambers. The results have permitted discussion 

 of the relationships of the Tetracoralla to other groups of Anthozoa, 

 the conclusion being that the}' are most nearly related to the living 

 zoanthid actinians. A paper has been already published, and another, 

 " The Fossula in Rugose Corals," is submitted for publication. 



Recent Corals. — Two papers devoted to the morphology of recent 

 coral polyps have been alread}' published during the year, and a 

 third is almost ready for publication. This summer an expedition 

 has been conducted to the Hawaiian Islands for the purpose of secur- 

 ing a series of Pacific corals for comparison with results already 

 published upon West Indian forms. About three months were spent 

 among the islands in the collection and study of the living corals. 

 Between thirty and forty species were secured, and material pre- 

 served for later investigation, while over fift^^ cases of dried specimens 

 were obtained for studies on variation. The collection includes 

 many types not yet studied morphologically, and others which afford 

 interesting comparison with West Indian types. 



A series of experiments upon the physiology and reactions of 

 living coral polyps were conducted, and important facts bearing 

 upon their method of feeding were secured, demonstrating that the 

 exudation of mucus plays an important part in the process. 



A collection was made of the Hawaiian shallow- water actinians to 



