636 INSECTA. 



Platysioma, Meig., differs in having the head more compressed transversely, so that the upper surface is more 

 slanting, and tlie antenns appear inserted in the middle of the face. 

 This naturally conducts us to Timia, Wied., and Mosillus, belonging to the next division. 



The eighth division, Gymnomyzides, is composed of small Muscides, with a short body, curved, 

 nearly glabrous, of a shining black colour, the head much compressed transversely, as in Platystoma, 

 without anv inferior prominence ; the scutellum advanced ; the abdomen short, depressed, and some- 

 times terminated by a small point, and the legs nearly glabrous. 



Celyphus, Dalin. (having the scutellum extended over the body), and 



Laujcania, Latr. (with the scutellum of ordinary size and the seta plumose), have the antennae longer than the 

 head. The others have them shorter. 



In some of these they are very short and wide apart, and lodged in impressed fossulae, the space between them 

 being elevated. 



Mosillus, Latr., has the first cell of the posterior edge of the wings almost closed ; Meigen divides them into two 

 subgenera,— T/»(/rt, with the abdomen 6-jointed, and Ul'uUa, with it 5-jointed. 



Homalura, Meig., with the abdomen 5-jointed, and 



Actora, Meig., with it 6-jointed, have the first cells of the posterior limb of the wings entirely open and 

 longitudinal. 



In others the antennae are nearly contiguous, and the cells of the posterior edge of the wing are always open. 



Giimnomnzn, Fall., has the antenn<e inserted beneath a sort of arch, and near the middle of the face. 



LoHc/uva, Meig., has them inserted higher, without any appearance of an arch. 



The second section of the Muscides, and which forms our ninth and last sub-tribe, the IIypocera, 

 consists of a single subgenus, distinct from all the jireceding in many respects. The palpi are always 

 external ; the antenna; inserted near the oral cavity, very short, terminated by a large globular joint, 

 with a very long seta ; the wings have only three oblique discoidal nerves, whence the name Trineura 

 given to them by Meigen ; the legs are very short and spiny, with the thighs large and compressed, 

 especially in the hind legs. They are extremely active, and form tlie genus Phora, Latr. ; Tri- 

 neura, Meig. 



Our second general section of the Dipterotis insects diiFers from the preceding in the 

 mouth, antennsE, and transformations, and other less important characters ; whence Dr. Leach 

 was induced to form them into a distinct order, Omalopicra. Those which terminate this 

 section have a certain relation with the hexapod wingless insects, composing our order of 

 Parasites, or the genus Pediculus of Linnaeus, 



This section forms 



THE SIXTH FAMILY OF THE DIPTERA,— 



The Pupipara (or the Nymphipara of Reaumur). 



The licad of these insects, seen from above, is divided into two principal portions, the posterior 

 being the jnincipal, supporting the eyes and receiving the anterior part in an emargination in front. 

 Tliis is also divided into two parts, the posterior being the largest, and supporting the antennie at its 

 sides ; and the other constitutes the mouth organs. The inferior and oral cavity of the head is occu- 

 pied merely by membrane, out of the extremity of which the sucker protrudes, arising from a small 

 bulb, or advanced peduncle, composed of two setae close together, and covered by two coriaceous, 

 narrow, elongate and villose plates, which act as sheaths. Whether these valves represent, as 1 pre- 

 sume, the palpi of other Diptera, or whether they are pieces of a sheath properly so called, as regarded 

 by M. Dufour, who has discovered two small bodies, which he takes for palpi ; it is not less certain 

 that the proboscis of these insects differs materially from that of the preceding Diptera, and that the 

 proboscis has in this case more resemblance to that of the Fleas, from which it is, however, removed 

 by the absence of articulations. In Melophagus the base of the plates of the suclcer is covered by two 

 small, coriaceous, triangular pieces, united, and forming a kind of labrum ; they seem to represent, in a 

 small degree, the two pieces which cover the base of the rostrum of the Flea. 



The body is short, Ijroad, flat, and defended by a solid or leathery-hke skin. The head is more 

 intimately united to the thorax than in the preceding families. The antennae, always situated at the 

 lateral and anterior extremity of the head, appear either under the form of a tubercle bearing three 

 seta;, or that of small hairy plates. The size of the eyes varies, being very small in some species. In 



