PROCEEDINGS OF THE ACADEMY AND AFFILIATED 



SOCIETIES 



BIOLOGICAL SOCIETY OF WASHINGTON 



The 594th regular meeting of the Society was held in the Assembly 

 Hall of the Cosmos Club, Saturday, March 22, 191 9, called to order at 

 8:00 p.m. by Vice-President N. Holuster; 33 persons present. 



The regular program was as follows: 



J. W. GidlEy: Notice of a large canid from the Cumberland Cave de- 

 posits. Mr. Gidley briefly referred to the discovery of these deposits 

 in western Maryland through the digging of a railroad cut and to his 

 explorations of them. He then described the remains of a large doglike 

 animal found in them by him. He pointed out its relationships to 

 modern wolves, coyotes, and to the doglike remains in the asphalt 

 deposits of southern California. 



A. C. Baker : Intermediates in the Aphididae and their relation to 

 alternate hosts. Rearing experiments have shown the existence of 

 adult intermediate forms in all species studied carefully by the writer. 

 These forms show modifications in nearly all important structural char- 

 acters. They occur between the forms on one host and between the 

 forms on a primary and a secondary host. Thus they indicate the 

 ultimate division of species, such as the latter, into two. In fact, 

 almost, this occurred in the experiments. Host races were developed 

 with such species as Aphis rumicis. These races differed in structure, 

 after 50 generations or more, and individuals of them nearly all died 

 when transferred to the host of their ancestors. 



Our American species of Anoecia on Cornus compared with specimens 

 from different parts of Europe (from H. Schouteden, Albert 

 TuLLGREN, and others) differs in sensory organs. Our species, as 

 reared, never developed the European characters. In most cases 

 it became modified in the opposite direction. Races were developed 

 which live the year round on grass roots, laying their winter eggs there. 

 These forms differed very distinctly in structure from those including 

 Cornus in their host cycle. In some sections of the country these, 

 or similar races, seem to be settled as definite species with definite 

 structure and definite reproductive and host habits. In our classifica- 



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