194 EDAVARD NORTON. 



The cocoon is simple, egg-shaped. It is sometimes fastened to 

 stems, lies sometimes on the surface of the ground, sometimes in the 

 earth. 



Westwood (Mod. Class, of Insects) mentions the European species 

 which attacks the gooseberry (jY. grossidarirf^} as having been seen in 

 as large numbers as a thousand on a single bush. Other species 

 are found upon the cherry, willow and elm. 



Westwood refers also to the larvtv; of several species which are soli- 

 tary in their habits, and others which form woody galls upon the stem 

 and also in the spongy rib of the leaf. In some of these giills but one 

 individual resides, and in others more than one in each gall. These 

 galls have mostly been observed upon the willow in Europe. In this 

 country Mr. Walsh has described a number of species bred from vari- 

 ous galls, mostly on the willow, and has made the further remarkable 

 discovery, that not only are some of these galls makers but others are 

 parasitical in the galls of other insects. He has found, too, that many 

 of these are so much alike in the imago state, that it is almost impos- 

 sible to separate them. It is difficult to give a hearty assent to 

 Mr. Walsh's "Incjuilines or Guest-flies," without further investigation. 



Many species have two broods in a season, of which the first is 

 doubtless the most productive. 



This is the most difficult genus of this family, because the species 

 are so numerous, (Hartig enumerates about fifty species in Europe,) 

 and presents so few salient points of diflerence, either in form or color. 



In addition to this, most of the species here named are described 

 from but one or two specimens, so that we have abundant room for fu- 

 ture corrections. 



Dr. Hartig has joined to this genus several sub-sections, under dif- 

 ferent titles.* 



•■■"Hartig, Die Blattwespen, Ac, p. 179. 

 1. Neinatus. — Wings, one marginal and three or four submarginnl opIIs. 

 Subgenus. — 1. Nematus.—y^ mgi, one marginal and three or i\>ur submarginal 

 cells. 

 Sec. 1. — Leptopus. Lanceolate cell closed in middle. 

 Sec. 2. — Nematus. Lanceolate cell petiolate. 



Tribe 1. — Orensus. The fir.st joint of hinder tarsi as usual. 

 Tri))e 2. — Neinatufs. Last joint of hinder tarsi as usual. 

 2. — Cryptocampus. Wings, one marginal and three submarginal 

 cells. 

 Sec. L — Crytoe.amj>us. Bod}' lengthened, cylindrical. 

 Sec. 2. — Diphadnus. Body egg-shaped, short. 



