NO. 15 SMITHSONIAN EXPLORATIONS, I92I 47 



are often kept about the houses for the purpose of ridding the 

 premises of insects and spiders. 



In addition many land shells and a considerable quantity of 

 ethnological material were secured. Doctor Abbott left New York 

 about the middle of December, 192 1, on another expedition to the 

 island, but thus far no information or material has been received 

 from him. 



EXPERIMENTS IN HEREDITY 



Progress in the experiments in heredity conducted under the joint 

 auspices of the Smithsonian and Carnegie Institutions by the writer, 

 Dr, Paul Bartsch of the U. S. National ]\Iuseum, have from time to 

 time been published in this pamphlet and in the Year Book of the 

 Carnegie Institution. A summary of the results attained up to 1920 

 was published as " Experiments in the Breeding of Cerions " in 1920, 

 volume 14 of the Department of Marine Biology of the Carnegie 

 Institution, pp. 3-55, pis. 1-59. 



The reported loss of the Cerion colonies introduced into the 

 Tortugas which were said to have been wiped out by the hurricane of 

 September. 1919, made it necessary to revisit the Bahamas to secure 

 additional breeding material for the heredity experiments. Accord- 

 ingly, passage was secured at Miami on the power schooner '' Tecoma " 

 for Nassau, New Providence, on j\Iay 18, and there the services of the 

 power boat " Standard J " were secured for a trip to Andros. 



The desired adolescent specimens of Cerion viaregis were obtained 

 along King's Road, Bastian Point, South Bight, Andros. with con- 

 siderable difficulty because the agricultural efforts on the part of the 

 local population have shifted to the ground that was occu])ied by the 

 Cerion colonies during our 1912 visit. 



The colony of Cerion casablancae has met with even greater mis- 

 fortune, for sheep and pigs have been introduced into the region 

 occupied by this species, and the larger vegetation has been cut down 

 in order to furnish more opportune habitat for grass culture. These 

 new environmental conditions promise well to exterminate this colony. 

 The necessary material for the experiments was secured with great 

 difficulty. 



A trip was next made through South Bight to the western end of 

 Andros and then back to the eastern shore through Middle Bight. On 

 this journey many stops were made and Cerions were gathered in 

 large numbers. The localities from which they were taken were care- 

 fully listed so that it will be possible to go back to the same spot in 



