of certain specie* of Willow. — Part 2nd. 229 



On p 569 of the same Paper I also showed, that Harris must have 

 heen mistaken in supposing, that the larva of the Wheat-midge 

 formed no cocoon when it went underground. Dr. Fitch, on p. GO of 

 the volume above referred to, explains how he made the interesting 

 discovery, that these larvae really do inclose themselves in cocoons, 

 agglutinated to the earth just as I had suggested ; and that " they do 

 not remain naked in the ground, as he had all along supposed them 

 to." The Wheat-midge, by the way, as is abundantly evident from 

 Harris's and Fitch's descriptions and figures, is a true Diplosis, and 

 consequently its correct name is Diplosis tritici, Kirby. In conse- 

 quence partly of the S having been unknown to European authors, 

 it is erroneously referred to the subgenus Cecidomyia, instead of to 

 that of Diplosis, by all authors known to me, including Osten Sacken. 

 {Dipt. X. A. p. 189.) The Hessian Fly, on the contrary, (C. de- 

 structor Say) really does belong to the subgenus Cecidomyia. 



The "two small oval lamels" described by Winnertz as attached 

 to the oviduct of a European Diplosis, aud suspected by me (Proc. &c. 

 III. p. 556) to be nothing but two eggs protruding, I have since no- 

 ticed in several Diplosis, when the oviduct is exserted to its utmost 

 length ; and they are not eggs but true parts of the oviduct. 



HYMENOPTER A.— Family Tentiiredtnid.e. 



For the sake of scientific precision, it may be as well to touch upon 

 a few points relative to the Natural History of this family. 



I. Authors originally described the Tenthredinidous abdomen as 9- 

 jointed in both sexes. (Late. Gen. Or. Insect., III. p. 225.) West- 

 wood first proved, that what had been previously considered as the 

 1st abdominal joint was in reality the metathoracic postscutellum, and 

 consequently that the abdomen here was really not 9-jointed but 8- 

 jointed. (Ittrod. II. p. 92.) And it is difficult to see how any one 

 could come to any other conclusion, after examining a Cimbex, a Hy- 

 lotoma, a Lyda, a Cephas, a Lophyrus, a Euura or a Nematus. For 

 in all these genera there is a large surface of membrane between the so- 

 called 1st aud 2nd abdominal joints, occupying the whole gaping 

 suture in Cimbex and llylotoma, and a more or less transverse triangu- 

 lar space on the dorsum in the other five genera; which membranous 

 space I call everywhere '-the basal membrane.'' And besides, in other 

 genera (Tenthredo, Dolerus, timjdiytus etc.) the so-called 1st joint is 

 split along the dorsal line; and it is every where the ventral arc corres- 

 ponding to this so-called 1st dorsal joint of the abdomen which bears 

 the hind legs, and which must necessarily therefore be metathoracic. 



