194 ENTOMOLOGICAL SOCIETY 



Mr. Banks whether these were Texas species and would intro 

 duce a new element into the spider fauna of the District of Co 

 lumbia. Mr. Banks replied that they were probably species which 

 were already wide-spread, since this is the case with nearly all 

 species of spiders which inhabit houses. 



Dr. Gill spoke at length on the subject of the relative value of 

 different groups of animals from the faunistic standpoint. He 

 showed that we must consider the problem not only from the 

 morphological but also from the paleontological standpoint and 

 illustrated this point in a somewhat detailed consideration of some 

 of the striking features of the vertebrate faunas of South America. 

 Africa and India, deducing from this consideration the conclusion 

 that the primitive faunas of South America and Africa were de 

 rived from the same common source, while the forms common to 

 or similar to each other in Africa and India were derived from a 

 common source at a later period. This means that South Amer 

 ica and Africa were connected at an early period and that the 

 connection between Africa and India was made at a comparatively 

 recent date. He contended that the fresh-water fishes are the 

 best group for the study of questions of geographical distribution, 

 largely on account of their necessary restriction to the bodies of 

 water which they inhabit. He showed that while the mollusks 

 in particular, and also the insects, have changed comparatively 

 little since relatively early geological times, the mammals have 

 changed very greatly and the fishes occupy in this respect a posi 

 tion intermediate between the mollusks and insects on the one 

 hand and mammals on the other. 



Mr. Banks stated, that, in his opinion, water forms are not as 

 good as land forms for the study of geographical distribution ; at 

 all events this is the case with aquatic insects and arachnids. 

 Fishes are bv no means so limited in their distribution as land 

 forms. 



Mr. Marlatt spoke of the extraordinary distribution of Bryobia 

 pratensis, which occurs from New England to California, and is 

 known in the mountains of Montana at an elevation of 7,000 or 

 S,ooo feet, remote from civilization, and also in the Southern 

 States. What is probably the same species also occurs in Europe 

 and in Australia. He considered this one of the most extraordi- 

 narv instances of distribution known. Mr. Banks thought that 



