338 



clip just 1 millimeter for each gram of teusioii exerted, aud therefore the 

 number of grams of tension is the same as the number of millimeters of 

 displacement, and both are read from the same scale. 



ADDITIONAL NOTE ON THE MEGILLA PARASITE. 



By C. V. Riley. 



Since the publication of our article on this subject (see p. 101, ante) 

 we have received an interesting letter on the subject from Rev. T. A. 

 Marshall, of England, who is monographing the Braconidte, and to 

 whom we sent specimens. He replies that the species belongs to the 

 genus Dinocamptus of Foerster, which he himself prefers to regard as a 

 subsection of the old genus Perilitus, and that the European species P. 

 terminatus (formerly placed in Microctonus by Ratzeburg, Ruthe, and 

 others), the habits of which are so similar to those of our American 

 species, belongs to the same subsection of the genus. Concerning our 

 own species Mr. Marshall writes : 



It differs very little from the cognate European forms, and is interesting to know 

 from your observations that it has similar habits. Its appearance confirms my notion 

 that such a genus as Dinocamptus is useless and should be suppressed ; for your in- 

 sect exhibits at the same time the dividing uervure of Dinocamptus and the abruptly 

 curved radial cell of Perilitus. 



Using, therefore, the same specific name proposed in our former art- 

 icle, the species may be described as follows : 

 Perilitus americanus n. sp. 



Female. — Length 3.5'""^; expanse 6'"°\ Head nearly smooth, thorax and first ab- 

 dominal segment punctate, abdomen glabrous. First cubital areolet separate from 

 the first discoidal ; radial areolet ending half way between the wing and the stigma, 

 serai-cordate. Terebra straight. Color black; antenu;c dark, pedicel and first fun- 

 icle joint yellowish; head, except ocelli and included spot and the large occipital 

 black spot, fulvous; middle aud hind coxte black, hind femora dusky, rest of legs 

 honey-yellow; wings hyaline, stigma dark brown, veins a trifle lighter, still lighter 

 in hind wings; most of abdomen dark fulvous approaching castaneous, dark on me- 

 diodorsal region. 



Resembles the European P. falciger Ruthe in venation, but differs in shape of ovi- 

 positor and radically in coloration. Differs decidedly in color from the only described 

 North American species — P. meUhius Provancher. 



Since the preparation of this additional note Messrs. 0. M. Weed 

 and C. A. Hart have published in Psyche, for April, 1889, an arti- 

 cle entitled " Notes on the Parasite of the Spotted Lady-beetle." 

 The authors have found a number of similar cases and, adopting our 

 name of Centistes aniericana, publish a full description of both sexes. 

 They have therefore fallen into the same error of generic position, and 

 their description seems to indicate that they had before them a differ- 

 ent species of Perilitus, although on actual comparison of type speci- 

 mens the differences may prove to be varietal. 



