INSECTA. 307 



the mandibles as maxillae. According to this view the mandibles 

 would be wanting.) These insects undergo complete metamorphosis. 

 At first the larva has six feet and two threads at the abdomen, 

 (somewhat the form of Lepisma}; afterwards these feet disappear, 

 for the insect then lives in the abdomen of larvae of Hymenoptera. 

 In these Hymenoptera, also, the parasite is changed into a pupa, 

 which in the perfect Hymenoptera projects between the rings of the 

 abdomen. The wingless female remains in this situation, and is 

 impregnated there. It is viviparous. The six-footed larvae, which 

 in the genus Xenos jump like Podurellce, were described by KLUG 

 and WESTWOOD, and previously also by YON SIEBOLD, as parasites. 



Comp. on this order W. KIRBY, Strepsiptera, a new order of 

 Insects, Linncean Transact. Yol. xi. 1815. pp. 86 122, Tab. 8, 9 ; 

 Addendum, pp. 233, 234 ; LEACH on the Rhipiptera of LATREILLE, 

 Zool. Misc. m. pp. 133 136 ; W. B. PICKERING, Observations on 

 the Economy of the Strepsiptera, Transact, of the Entomol. r /Soc. 

 London, i. 1836, pp. 163 172, PL xvn ; J. O. WESTWOOD, Descrip- 

 tion of a new Strepsipterous Insect, ibid. pp. 173, 174, PL XVIL 

 fig. 15 ; C. TH. v. SIEBOLD, Ueber Xenos Sphecidarum und dessen 

 Schmarotzer, Beitrage zur Naturgeschichte der Wirbellosen Thiere, 

 1839, s. 7287, Tab. in. figs. 6274; by the same Ueber Strep- 

 siptera, in ERICHSON'S Archiv f. Naturgesch. ix. 1843, s. 137 162. 

 Tab. vn. 



Family VIII. Strepsiptera s. Stylopidce. [Characters of the 

 rder.] 



* Tarsi with four joints. 



Xenos 1 Rossi. Antennae bipartite, single at the base, triarticu- 

 te, with first joint obconical, longer, with branches semi-round, 

 cuminate ? not articulate. 



Sp. Xenos Peckii, KIEBY, Linn. Trans. Tab. 8, Tab. 9, fig. i, KIRBT and 

 SPENCE, Introd. to Entom. i. PI. n. fig. i; the larva infests Polyste fucata 

 (nor. Amer.) ; &c. European species are Xenos Rossii and Xenos Sphe- 

 cidarum. They are all small insects whose body is only about ig line 

 long. 



Stylops KIEBY. Antennas bipartite with stem single, biarticu- 

 ite, upper branch triarticulate, (Antennas have six joints, the third 



a guest ; because harboured by other insects. 



202 



