632 INSECTA. 



Bucentes, Latr. (Rtomoxys, Fab., Siphona, Meig.), has the proboscis elbowed twice, as in Myopa. 

 Camus, which Nitzsch refers to this family, is distinguished by having only the rudiments of wings ; the direc- 

 tion of the proboscis, and the form of its antennae and body, seem to indicate that it comes near Stomoxys. 



The fourth and last tribe, Muscides, is distinguished from the preceding by having a proboscis 

 always very apparent, membranous, and bilabiate, generally bearing two palpi (except in Phora), and 

 capable of being entirely withdrawn into the oral cavity, and a sucker of two pieces. The antennae 

 always terminated by a palette with a lateral seta. 



These Athericera embrace the ancient genus Musca of Fabricius, which the works of Fallen and 

 Meigen (without speaking of our own) have singularly modified. The difficulties, however, which 

 oppose its investigation, are nevertheless far from removed ; for although these authors have estab- 

 lished a great number of genera, there are, nevertheless, some, such as Tachina and Anthomyia, which 

 can only be regarded as magazines. In the work of Meigen, which is confined to the European 

 Diptera, the first of these genera comprises 315 species, and the second 213. Dr. Robineau Desvoidy, 

 anxious to complete these researches and serve science, has undertaken with much zeal the special 

 study of the Muscides, which he terms Myodaires, and has presented a memoir upon the subject to the 

 Royal Academy of Sciences, [since published]. As Latreille, however, was only acquainted with the 

 general distribution of this tribe through the report of M. de Blainville, presented to the Academy, he 

 was not able to make use of it : indeed, it would too far exceed the limits of this work to do so, and 

 probably alarm young naturalists by the multitude of genera which he has established, and which 

 appeared to the reporter to be too slightly characterized. We think that the work of Meigen, except 

 in respect to the revision of the two genera above mentioned, is quite sufficient, in the actual state of 

 the science. [The vast extent of this tribe, which probably equals that of all the other Diptera united 

 together, has, notwithstanding the remarks of Latreille, rendered the establishment of many additional 

 genera requisite. M. Macquart, in his Histoire Naturelle des Dipteres, and Messrs. Haliday and 

 Walker, in various detached memoirs, have added to the number of those proposed by Meigen, although 

 they have materially reduced the number proposed by Robineau Desvoidy, which amounted to 354, 

 divided into ten primary groups, two of which still remain unpublished, and which will of course 

 increase the number of his genera.] 



This tribe comprises the genus 



Musca. 



The first section comprises those species which have the antennae inserted near the forehead ; the 

 palpi placed upon the proboscis, and retractile with it into the oral cavity, and transverse nerves to the 

 wings. This section comprises eight principal groups, or subtribes. 



The first division (Creophil^b) has very large alulets, nearly covering the balancers. The wings are 

 generally apart, with the two terminal and external cells of the posterior limb closed by a transverse 

 nervure. 



Some of these have the epistome not beak-like, and the sides of the head not advanced into horns. 



A portion of these have the seta of the antennae naked. 



Echhiomyia, Dumeril, has the second joint of the antennae longest ; the last is nearly trapezoidal, with the seta 

 biarticulate at its base. Musca grossa, Linn., the largest known species, nearly as large as a Humble-bee. It is 

 black, very bristly, with the head buff, eyes brown, and base of the wings reddish. It makes a loud buzzing, 

 settles upon flowers in woods, and often upon cow-dung, on which its larva resides ; the body of which is yellowish, 

 shining, conical, with a single hook, and two fleshy horns at its anterior extremity; the other being terminated 

 by a circular plate, upon which are two spiracles, each placed upon a lenticular lobe, elevated in the middle. 

 The segment after the head is also furnished on each side with a spiracle. In the cocoon of the pupa, which is 

 also conical, the posterior extremity also presents two more distinct spiracles ; its contour formed by a plate with 

 nine flaps. [It appears to me that Latreille has erred in referring Reaumur's figures to Echhiomyia grossa. They 

 seem to me to be those of the transformations of Hesembrina meridiana. I presume that the larva of Echhiomyia 

 grossa is a parasite.] 



In the other Creophilae the third joint of the antennae is never shorter than the second. Sometimes the face is 

 nearly naked, and never clothed with long bristles. 



Gonia, Meig., has the seta of the antennae elbowed, and the abdomen with distinct segments, and convex. 



Mil to gramma, Meig., has the abdomen also convex, with distinct joints, and the seta of the antennae straight. 



Trixa, Meig., differs from Miltogramma in having the third joint of the antennae scarcely longer than the 

 second. 



In the four following subgenera the abdomen is swollen, with the articulations indistinct, or flattened. 



