242 PROCEEDINGS OF THE ACADEMY OP 



halterum capitulo infuscatis ; alis pallide fusceseentibus, pilosis. Long 

 lin. 3. 



Proboscis and palpi fuscous ; front and vertex infuscated in the middle, 

 cinereous near the eyes ; antennae fuscous, with long verticils, and apparently 

 17-jointed. Thorax tawny, a little darker on the praescutum, pleura? paler ; 

 metathorax pale brown ; halteres pale at base ; knob infuscated ; feet tawny, 

 slightly hairy, infuscated at the tip of femora and tarsi. Tergum brown, venter 

 paler ; valves of 9 ovipositor long, narrow, sharp, and but slightly curved. 

 Wings infuscated, covered with a short, sparse, almost microscopic pubescence, 

 which is evenly spread over the whole surface ; it is not woolly, like in E r i o p- 

 t e ra and does not affect much the transparency of the wing. The stigma is 

 indistinct ; the second radial area is nearly equal in length to the cubital ; the 

 three central cross-veins form almost a straight line ) the mediastinal cross- 

 vein is near the tip of the mediastinal vein. 



A single $ specimen. Trenton Falls (nob.) 



This species has a striking resemblance with Ula pi 1 o s a : the latter, how- 

 ever, is easily distinguished by the position of the mediastinal cross-vein, which 

 is remote from the tip of the mediastinal vein ; by the hairy eyes, the longer 

 palpi, and the valves of the 9 ovipositor, which are much shorter, broader 

 and more curved. 



Trichocera Meig. 



This genus is mentioned here with the purpose only of showing its affini- 

 ties. 



It is allied to genus Limnophila nob., by the neuration of the wings 

 (two radial area, petiolate areolet, etc.,) its spurred tibiae with smooth ungues 

 and distinct pulvilli ; although the joint of the antennae are indistinct, as in 

 Limnophila. (See his remark to plate xxvi. fig. 8, in Walker's Ins. Brit. 

 Dipt. vol. iii.) 



But Trichocera differs from Limnophila nob., by the position of the 

 mediastinal cross -vein, which is at a moderate distance from the tip of the 

 mediastinal vein, although not anterior to the origin of the petiole, by the short- 

 ness and incurved direction of the axillary vein and by the length of the last 

 joint of the palpi. 



The American species in my collection appear to be identical with the Euro- 

 pean species of this genus ; I would not venture to describe them, therefore, 

 before having carefully compared them with specimens from the other conti- 

 nent. 



Anisomera Meig. , 



The characters of the only North American species in my possession agree 

 with those of this genus as defined by Meigen, Zetterstedt and Walker. The 

 wings are exactly like Meig. i. tab. vii. f. 8. I perceive but six joints in the 

 antennae of the 9 ana " not ten as Mr. Westwood does (see Walk. Dipt. Brit. iii. 

 tab. xxvi. f. 9.) 



Like Arrhenica and E r i o c e r a, this genus is allied to Limno- 

 phila nob., by its two radial areae, the spurs at the tip of the tibiae, the dis- 

 tinct pulvilli and the form of the <^ genitals. 



A. megacera. Obscure cinerea, thorace vittis tribus fuscis; antennis tf 

 corpore longioribus, nigris ; pedibus nigris, femoribus basi pallide fuscis ; alis 

 snbeinereis ; long. lin. 2f. 



Head cinereous, brownish on the front ; palpi and antennae black ; the latter, 

 in the <$, by the one-half longer than the body with a fine pubescence ; their 

 basal joints short, the tip of the third reach considerably beyond the base of 

 the wing ; the fourth, fifth, and sixth are about equal in length and a little 

 shorter than the third ; antennae of the 9 short, not reaching the base of the 



[Aug. 



