84 NEW YORK STATE MUSEUM 



the different genera. In C h i r o n o m u s and allied genera 

 there is no trace of mandibles. In Geratopogon the mouth 

 parts are fitted for piercing. For homologies of the mouth parts, 

 see Kellogg's papers in Ps3'che, 1899. The antennae or feelers are 

 variable in form and number of joints; the first visible joint (called 

 2d joint hy Miall and Hammond 1900) is usually enlarged, fol- 

 lowed by a second which is sometimes also somewhat enlarged, 

 these two being called the scape. These are always more or less 

 differentiated from the remainder, which constitute the flagellum. 

 In the male the joints of the flagellum are usually provided with 

 long hairs. The first joint of Miall and Hammond (1900) is the 

 extremely short hidden one, which is sunk in the head, and almost 

 entirely occupied by the muscles which move the antennae to and 

 fro. The next joint, the large one, exhibits a peculiar structure, 

 which is believed to serve for the perception of sound. (M. and H. 

 1900, and Mayer 1874.) The head is connected with the thorax 

 by a neck, whose cuticle is membranous. 



The thorax is composed of three parts, the prothorax, the meso- 

 thorax and metathorax. The prothorax is quite narrow, forming 

 a rounded collar back of the neck, within which are the muscles 

 of the foreleg. On the dorsal surface it appears as a narrow band 

 with a median incisure and suture. The humerus or humeral 

 callus belongs also to the prothorax according to Miall and Ham- 

 mond (1900). It is called the paratreme by Lowne. The meso- 

 thorax is very large; it is highly arched, and in some it projects 

 somewhat over the head. On its fore edge is the anterior thoracic 

 spiracle. The upper or dorsal surface of the mesothorax is often 

 called the mesonotum, and it has attached to it at its posterior 

 margin, and cut off from it by an impressed line, the scutellum, a 

 small, semioval body, which really belongs to the mesothorax (see 

 pl.31, fig.l6, Ohasmatonotus). The wings are attached to 

 each side of and just below the scutellum. Behind and beneath the 

 scutellum is a smooth and rather prominent oval-arched portion, 

 the metanotum or upper portion of the metathorax (or post scutel- 

 lum of Miall and Hammond 1900) . Below and between the fore and 

 middle legs is a very prominent hemispherical part (especially in 

 Chironomus), the mesosternum. The sides of the body in 

 front of the wings are called the pleura, and the under surface of 



