RHIPIPTERA. 311 



anolgous to those observed at the anvis of the above mentioned 

 Hemiptera. The six legs are almost membranous, compressed, nearly 

 equal, and terminated by filifrom tarsi composed of four membranous 

 joints with, as it were, vesicular extremities; the last is somewhat 

 larger than the others and presents no hooks. The four anterior legs 

 are closely approximated, and the two others thrown behind. The 

 space on the pectus comprised between these latter is very considerable, 

 and divided by a longitudinal furrow. The posterior extremity of 

 the metathorax is prolonged over the abdomen in the manner of a 

 large scutellum. The sides of that metathorax, which give insertion to 

 this last pair of legs, are strongly dilated behind, and form a sort of in- 

 flated shield that defends the exterior and lateral base of the abdomen. 



These Insects, in their larvae state, live between the abdominal 

 scales of several species of Andrenoe and wasps of the subgenus 

 Polistes. They frisk about with a simultaneous motion of the wings 

 and halteres. Although they appear to be removed in several respects 

 from the Hymcnoptera, I still think it is to some of those Insects such 

 as the Eulophi, that they are most nearly allied. 



M. Peck has observed one of the larvse — Xenos PecMi — which is 

 found on Wasps. It forms an oblong oval, is destitute of feet, and 

 annulated or plaited ; the anterior extremity is dilated in the form of 

 a head, and the mouth consists of three tubercles. These larvae 

 become nymphs in the same place, and, as it appeared to me when 

 examining the nymphs of the Xenos Rossi, another Insect of the 

 same order, within their own skin, and without changing their 

 form *. 



Nature has perhaps furnished the Rhipiptera with the two false 

 elytra, of which we have spoken, to enable them to disengage them- 

 selves from between the abdominal scales of the Insecis on which 

 they have lived. 



They are a sort of Q^siri to Insects, and we shall soon find a 

 species of Conops that undergoes its metamorphosis in the abdomen 

 of the Bombi. 



The Rhipiptera form two genera. 



Stylops, Khb. 



The first one observed and instituted by M. Kirby. The superior 

 branch of the last segment of the antennae is composed of three little 

 joints. The abdomen is retractile and fleshy. 



But a single species is known; it lives on the Andrense. 



* For some observations on this Insect, see a very good Memoir of M. Jurine, 

 Sen. 



