352 
[Assembly 
The Fly. Its Characters. —In the female, (fig. 3,) the head is 
flattened globular, and black throughout. The antennal (fig. e,) are 
about half as long as the body, and composed of sixteen joints, each 
of a cylindric-oval form, the length being about double the diame¬ 
ter ; each joint is clothed with a number of hairs, of which those 
towards its base are slightly more robust and longer, about equal¬ 
ling the joint in their length, and surrounding it in a whirl. The 
joints are separated from each other by very short translucent fila¬ 
ments, having a diameter about a third as great as the joints them¬ 
selves. The terminal joint is at least a third longer than the pre¬ 
ceding ones. The two basal joints of each antenna are globular, 
and compact or not separated by an intervening filament, and ex¬ 
ceed the following joints in diameter. The palpi (fig. /,) consist 
of three obvious joints, clothed with very short minute hairs. The 
two last joints are cylindrical, nearly equal in size, and about twice 
as long as broad : the basal joint is more short and thick. The 
thorax is oval, broadest immediately back of the wing sockets, and 
black. The scutel is of the same color, projecting, and slightly 
polished, with the suture surrounding it sometimes fulvous. The 
poisers are dusky. The abdomen is elongate-ovate, its broadest part 
scarcely equalling the thorax in diameter; it is of a black color 
above, more or less widely marked at the sutures with tawny-ful¬ 
vous, and furnished with numerous fine blackish hairs. The ovipo¬ 
sitor is rose-red, and slightly exserted commonly in the dead speci¬ 
men; it is susceptible of being protruded to a third of the length of 
the abdomen. The wings are slightly dusky, and fulvous at their 
insertion into the thorax. Their form and neuration is identical 
with that of the other species of this genus, except that the slight 
connecting nerve between the mediastinal and postcostal is common¬ 
ly wanting, and the medial and forks of the anal nerves are extreme¬ 
ly faint for a species o! Cecidomyia so large as this. The legs are 
detect, except tliat its larva case is of a pale brown color, untingod with rufous or 
castaneous. It infests the Agrostis lateriflora ?, numbers dwelling together in an 
imbricated gall, somewhat resembling the fertile aments of the hop, though larger, 
and connected with the main stalk by a short pedicel which is inserted into one of the 
lowest joints of the culm. From the coriaceous texture of the larva ease, I suspect 
the inclosed worm will not leave it, until transformed to a pupa and upon the point 
of evolving the perfect fly. 
