64 Report of the President 



Excellent progress has been made in the delicate and diffi- 

 cult modeling of the parts of the complicated Rotifer Group, 

 by Mr. Mueller, Mr. Olsen and Mr. Southwick, under the 

 supervision of Mr. Miner, with the invaluable cooperation 

 and advice of Mr. Myers. This group, as reported last year, 

 will be a companion piece to the Bryozoa Group, and will be 

 installed in a similar case. The microscopic fresh-water Roti- 

 fers which will be represented are highly magnified, have 

 considerable complexity of structure and require much pre- 

 liminary research in the field and with the microscope. The 

 assistance of Mr. Myers, and his accurate knowledge of these 

 forms, have been indispensable in this respect, while Mr. 

 Mueller's careful manipulation of the complicated glass 

 models is worthy of especial note. 



The original material for the exhibit showing variation 

 within the species was donated by Professor C. B. Daven- 

 port of the Carnegie Laboratory at Cold Spring Harbor, 

 L. I., and has been a provisional exhibition in the Darwin 

 Hall for some time. During the past year, this has been re- 

 arranged and remounted on a chart, which in its completed 

 form gives a striking illustration of natural oscillation about 

 the norm of the species, as illustrated by a pailful of scallops 

 (Pecten) picked up at random on the beach. 



Three individual models of Rotifers have been prepared 

 for the synoptic series, to show, greatly enlarged, character- 

 istic features of the anatomy and the feeding adaptations of 

 certain species. A series of models for an exhibit illustrat- 

 ing the Phylogeny of the Animal Kingdom, with special ref- 

 erence to the origin of the mammalian stem, has been pre- 

 pared for installation in the Synoptic Hall of Mammals and 

 is now practically complete. 



As in former years, the Darwin Hall has been extensively 

 used by teachers and classes from the public schools, high 

 schools and colleges of Greater New York and 

 Educational * ts surr oundings. The total number of pupils 

 Work in the visiting the hall in this way during 1921 for 

 Darwin Hall purposes of study was 17,845, of which 15,789 

 were public school pupils, 1,558 came from pri- 

 vate and parochial schools, and 498 from colleges and uni- 

 versities. 



