ANISOMERA. 243 



the genus Anisomera, of which he had received a drawing and 

 description ; the latter by Wiedemann. 



In 1830 Meigen (Vol. VI, p. 291) recognized the identity of 

 Nematocera and Anisomera, and dropped the former name. 



Curtis (Brit. Entom. 589), in 1836, introduced the genus Pero- 

 necera, already mentioned above. 



A detailed account of all the European species and the history 

 of each, has been given by Mr. Loew in his often quoted article. 

 The coloring of the European species seems to be rather uniform: 

 blackish-gray, with darker stripes on the thorax ; the only known 

 American species agrees in this respect with them. 



The name Anisomera is derived from aWoj, unequal, and ^£>oj, 

 part, in allusion to the structure of the antennae. 



Description of the species. 



1. A. megacera 0. S. $ and J.— Obscure cinerea, nigrescens ; 

 thorace vittis tribus obscuris ; antennae maris corpore toto longiores ; 

 feminae thorace breviores ; vermla transversa marginalis pedunculo 

 cellulae submarginalis primae inserta. 



Dark gray, blackish ; thorax with three dark stripes ; antennae of the male 

 longer than the whole body ; those of the female shorter than the thorax ; 

 marginal cross-vein inserted on the petiole of the first submarginal cell. 

 Long. corp. 0.27—0.3. 



Stx. Anisomera megacera 0. Sacken, Proc. Ac. Nat. Sc. Phil. 1859, p. 242. 



Head dark gray, almost blackish in the middle ; palpi and an- 

 tenna? black ; the latter, in the male, nearly once and a half the 

 length of the body, finely pubescent ; basal joints short ; flagellum 

 filiform ; first joint very long (if bent backwards, it would reach 

 the basis of the abdomen) ; the second and third also elongated, 

 although somewhat shorter than the first ; the remaining portion 

 of the antennae is a little shorter than the third joint of the 

 flagellum. The antennae of the female are short (bent back- 

 wards, they would hardly reach the root of the wings) ; the third 

 joint is the longest; the sixth is very short, almost rudimental. 

 Thorax dark gray, with a yellowish reflection ; a brownish, 

 cuneiform intermediate stripe, with a faint pale longitudinal line 

 in the middle ; the two lateral stripes are much abbreviated in 

 front, and extended beyond the suture behind ; a soft, short, 

 hardly perceptible yellowish pubescence between the stripes -, 

 halteres more or less dusky ; feet brownish, femora somewhat 



