DIPTERA. 349 



prison by driving off the anterior portion. Sec Reaumur, In- 

 sect., IV, Mem,, IV and I. 



S. Reaumurii, Meig. Differing from the cuprarius in the 

 abdomen, most of which, or at least the base, is of a blood-red, 

 or a brighter tint of the same colour *. 



Vappo, Lat., Fab. — Pachygaster, Meig. 

 Only differing from Sargus in the antennae, which are still shorter, 

 with the two first joints shorter or wider, or altogether transversal f. 



Our second general division of the Diptera, which are provided 

 with a sucker enclosed in the sheath, and whose antennae consist of 

 but three or two joints, comprises those whose proboscis, usually bi- 

 labiate, long, geniculate, and bearing the palpi a little above the 

 elbow, is most commonly entirely contained in the oral cavity, and 

 when, always salient, has a sucker composed of only two pieces. The 

 last joint of the antennae, always accompanied by a stilet or seta, never 

 exhibits annular divisions. The palpi, when at rest, are concealed. 



This division will form our fifth family. 



FAMILY V. 



ATHERICERA, 



Where the proboscis is usually terminated by two large lips. The 

 sucker is never composed of more than four pieces, and frequently 

 presents but two. 



The larvse have a very soft, extremely contractile, annulated body, 

 narrowest and most pointed anteriorly. The head varies as to figure, 

 and its external organs consist of one or two hooks, accompanied in 

 some genera by mammillae, and probably in all by a sort of tongue 

 destined to receive the nutritious juices on which they feed. They 

 visually have four stigmata, two situated on the first ring, one on each 

 side, and the two others on as many circular, squamous plates, at 

 the posterior extremity of the body. It has been observed that these 

 latter, at least in several, were formed of three smaller and closely 

 approximated stigmata. The larva has the faculty of enveloping 

 these parts with the marginal skin, which forms a sort of purse. 

 They never change their skin. That which invests them when 

 first hatched becomes indurated, and thus forms a sort of cocoon for 



* See the same authors, 



Wiedememann, in his " Analecta Entomologica," has figured a Brazilian species, 

 the S. fwcifer, remarkable for the scutellum being armed with a long spine, forked 

 at the extremity. 



t See the same authors. 



