NATURAL SCIENCES OF PHILADELPHIA. 219 



brownish ; two or three basal joints yellow. Thorax pale brownish yellow, 

 with light vestiges of an intermediate capillary and two lateral stripes ; pleurae 

 with a hoary reflection : halteres pale yellow ; feet pale yellow, pubescent, and 

 slightly infuscated at the tips of femora, tibiae and tarsi. Abdomen yellowish 

 tawny ; male forceps somewhat different from that of the preceding species, the 

 interior falciform appendage forming a simple and not a double curve, as in D. 

 nigripes; it is short and has some bristles at the tip. The wings have a 

 brownish-cinereous tinge, more yellowish along the anterior margin ; the 

 neuration is almost like that of the preceding species ; veins finely pubescent. 

 Single (^ and 9 specimens from Dalton, Ga. (July, 1859.) 

 A female specimen from the same locality is more brownish grey on head 

 and thorax. I am not sure if it ought to be considered as a distinct species. 



Antocha nob. 



Mediastinal vein indistinct, being closely applied to the subcostal vein.* No medias- 

 tinal cross-vein apparent. Petiole not arcuated near its origin, but straight, and 

 forming an acute angle with the subcostal vein. Anal angle of the icing almost square, 

 and, in consequence of this, the subaxillary area is nearly triangular. Excepting 

 these peculiarities, the neuration is like that ofDicranomyia Steph. ; that 

 is, there is one radial area, a discal, and no petiolate areolet. Antenna?- 16 jointed, 

 short (longer than the head, but not reaching the base of the wing) ; joints of 

 the flagellum subglobular ; last joint elongated ; all joints beset with short 

 hairs, the rf antennas being more thickly clothed with them ; verticils short. 

 Proboscis short. Palpi shorter than the head, first joint elongated, second and 

 third shorter, the fourth elongated. Tibia; icithout spurs at tip and without dis- 

 tinct pulvilli. Ungues with two small teeth near the base. Forceps of the (J 1 like 

 fig. 11, showing more analogy to the type ofLimnophila nob. than to that 

 of L i m n o b i a nob. 



The general appearance of the insects of this genus is very like that of 

 Dicranomyia. Antocha is related to all L i m n b iie with one radial 

 area, by the analogous neuration of its wings and the structure of the feet, (no 

 spurs, no pulvilli and toothed ungues). But it is dis'inct from them and approaches 

 the Limnobiae toith two radial arcce (Limnophilae, etc.) by the number of 

 joints of the antennae, and, apparently, by the structure of the ^ forceps. 



The wings of both species described below have a peculiar milky-whitish 

 tinge; they are distinctly iridescent, when held obliquely towards the light. 

 Besides, they show another peculiarity: it requires a magnifying power of 150 

 to discover the microscopic pubescence on their surface ; so magnified, they 

 appear covered with black dots, emitting very short hairs. (Much less power 

 is required to show the pubescence on the wing of most of the other L i m- 

 n ob iae.) 



The name of the genus is derived from its principal charac*er, the proximity 

 of the mediastinal and subcostal veins. 



A. saxicola. Cinerea, antennis, pedibusque fuscis ; coxis, femorum, 

 alarumque basi pallide flavis ; long. lin. 2h 3. 



Head cinereous ; proboscis yellow ; palpi and antenna? black. Thorax cinere- 

 ous, with several tawny, more or less distinct spots on the collare, the humeri 

 and the pleurae; praescutura yellowish cinereous, with three fuscous, almost 



* In order to ascertain this peculiarity of ihe neuration with more precision, I com- 

 pressed a wing of A. saxicola between two glass plates. This straightens the fold 

 usually existing in the L i m n o b i a between the costal and subcostal veins and shows ihe 

 course of the mediastinal vein with greater distinctness; in this c^se this vein appeared 

 separated from the subcostal by a narrow inlerval for about one-third of its length only ; 

 beyond that both veins ran close alongside of each other, till costal, subcostal and medi- 

 astinal converged in a stout and elongated anastomose. Under such circumstances there 

 was evidently no room for a mediastinal cross-vein. 



1859.] 



