388 ENTOMOLOGICAL SOCIETY 



unknown to me, but they must occur in immense numbers ; per 

 haps they are foreigners to our country and come sailing through 

 the air from the distant shores of the West Indies and Pacific 

 Islands. 







In the discussion of this paper Prof. Riley stated that before 

 the chemical and microscopical test had taken place he had been 

 inclined to consider this substance as silk of Asclepias, which had 

 repeatedly been found in large quantities, massed together by 

 storms. Spiders' silk when collected in quantities presented an 

 appearance quite different from the substance exhibited by Dr. 

 Marx. 



Dr. Marx emphasized the fact that upon chemical examination 

 the substance was found to contain no cellulose ; hence it could 

 not be of a vegetable nature. He was inclined, therefore, to con 

 sider it as a spider's web, although no remnants of spiders had 

 been found adhering to it. 



Dr. Stiles said one could not always distinguish vegetable from 

 animal substance by chemical analysis ; cellulose was found not 

 only in plants, but also in animals, e. g., the Tunicatesand others. 

 Plants, however, always presented a distinct cellular structure, and 

 if the substance under consideration was really amorphous it 

 must be the product of animal glands. 



Mr. Schwarz said that if the substance was spiders' web it 

 must have greatly changed by long exposure to atmospheric in 

 fluences. Its simultaneous occurrence at so widely distant points 

 seemed to indicate that it came either from Asia or Europe, where 

 gossamer spiders were much more numerous than in North 

 America. 



The subject was further discussed by several other members, 

 but no definite conclusion was reached. 



Mr. Howard read the following papers by Mr. Townsend : 



NOTES ON SOME CECIDOMYIID^ OF THE VICINITY OF 

 WASHINGTON, D. C. 



By C. H. TYLER TOWNSEND. 



Cecidomyia serrulaice O. S. Two dozen or more galls of 

 this species were found at Vienna, Va., Nov. 23, 1890, on Alnus 

 serrulata. Osten Sacken describes the gall perfectly. It is 

 whitish, hard and brittle, and has a calcareous or limy appear- 



