OF WASHINGTON. 61 



(when near a railroad), pebbles, crystals, and small sticks. 

 Mr. Barber believed that the ants cover their nests with these 

 darker substances to conserve the heat. Mr. Knab thought 

 that the crust is always composed of material gathered from 

 the surface of the surrounding region. Mr. Caudell believed 

 that the crust is simply for protection from wind and storm. 

 Mr. Titus concurred in this and described his observations on 

 the construction of the nests of a Pogonomyrmex in Colorado 

 and the effect on the broken and unfinished nests of a high 

 sweeping wind or a severe rain storm. He did not believe 

 that the heat-conservation theory would hold, since in some 

 regions the nests are covered with white crystals. It did not 

 seem likely to him that an ant would place black substances 

 on its nest along the railroad for any such definite purpose, 

 while the same species, a hundred yards away, took white and 

 red sand and gravel. Doctor Uhler described the large nests 

 of Camponotus pennsylvanicus DeG. found by him near. Balti 

 more several years ago, stating that these nests were some 

 times 9 feet high and 10 feet across. 



Mr. Pierce exhibited a large series of photomicrographs 

 taken by Mr. Barber, illustrating the morphology of some 

 of the American Strepsiptera. Inasmuch as the subjects of 

 these negatives are types, the negatives were denominated 

 phototypes. The most important features brought out were 

 the specific differences in the shape of the female cephalo- 

 thorax, and also the differences in the triunguloids, or first 

 larvae. One print demonstrated well the fact that the female 

 metathorax is a part of the cephalothorax. A number of 

 prints showed the metathoracic spiracle of the female, and' 

 indicated the trachese as well. Mr. Pierce stated that up to* 

 that time no species had been found by him to inhabit more 

 than one species of host. The different species are very 

 readily recognizable from the females. Manuscript was 

 then well in hand describing the various females and giving 

 illustrations, as well as monographing the existent knowledge: 

 of the order. 



Considerable discussion followed on the manner of distri 

 bution of triungulins, especially those of the remarkable meloid 

 beetle Hornia. 



