490 INSECTA* 



some, and almost cylindrical or in the form of an elongated cone in 

 the others. The wings are usually incumbent on the body. The 

 tarsi are furnished with three pellets. 



These Insects may be united in one generic section. 



XYLOPHAGUS. 



In Xylophagus proper, the body is narrow and elongated, and the antennae 

 are evidently somewhat longer than the head, and terminated by an almost 

 cylindrical joint. The head is short, transversal, and without any particular 

 elevation anteriorly. 



In the third section Stratiomydes, Lat., we also find antennas 

 consisting of three joints, the last of which, exclusive of thestilet or 

 seta, presents at most five or six rings. This stilet, or that seta, 

 exists in almost all of them, and in those where they are wanting, 

 the third joint is elongated and fusiform, and always divided into five 

 or six rings. The wings are always incumbent one on the other. 

 In several of those species where the antennas terminate in a some- 

 what oval and globular club, and always furnished with a stilet or a 

 seta, the scutellum is not spinous. 



This section comprises the genus 



STRATIOMYS, Geoff. 



In Stratiomys, properly so called, the antennae are much longer than the 

 head> the first and last joint being greatly elongated; the latter is fusiform, 

 or resembles a narrow and elongated club, narrowed at both ends, consist- 

 ing of at least five distinct rings, without an abrupt stilet at the extremity. 

 The two rings that compose it are not distinguished from the others by any 

 sudden contraction. 



The body of the larvae is long, flattened, invested by a coriaceous or firm 

 skin and divided into annuli, of which the three last form a tail terminated 

 by numerous plumose hairs which radiate from the extremity. They in- 

 habit water. 



Our second general division of the Diptera, which are provided 

 with a sucker enclosed in a sheath, and whose antennas consist of 

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

 bilabiate, 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 antennas, always accompanied by a stilet or seta. 



