NO. 1925. STUDIES IN THE SUPERFAMILY 0RY880IDEA—R0HWER. 145 



foveolate furrow. Third to seventh (inclusive) tergites normal. The 

 eighth tergite produced posteriorly so as to be longer in the dorsal 

 middle. First sternite reduced to a very .small plate which is present 

 in the middle only. vSecond to fifth (inclusive) sternites normal, ex- 

 tending much beyond the apical margins of the corresponding tergites. 

 Sixth sternite emarginate in the _ _ 



apical middle. Seventh sternite 

 lengthened in the middle where it 

 is di^^ded by the sheath (first gona- 

 pophyses). Eighth sternite long, 

 bearing two longitudinal carinas 

 which inclose an area called the 

 hypopygidium. These carinse 

 curve outward and upward at the 

 apex and define a small, somewhat 

 circular area. The eighth sternite 

 is grooved down the middle. In 

 this groove the ovipositor (second 

 and tliird gonapophyses) rests so 

 it appears to issue, when in normal 

 position, from between the eighth 

 sternite and eighth tergite, but in 

 truth it is exserted between the sev- 

 enth and eighth sternite. Sheath 

 very short, not nearly as long as 

 the ovipositor. Spiracles wanting, 

 or concealed, when the abdomen is 

 held in normal position, by imbri- 

 cation as in the forficuhds, beyond 

 the fu'st tergite. Cerci wanting. 

 In the male the abdomen has the opening apically, the genitalia con- 

 cealed, and the apical sternites regular in outline and no defined area 

 on the eighth sternite. (See fig. 5.) 



RELATIONSHIPS OF THE SUPERFAMILY. 



The superfaniily Oryssoidea is a very distinct group in the sub- 

 order Chalastogastra and is perhaps the most highly specialized 

 group within the suborder. By the older writers they have been 

 considered as a group witliin the Siricidte (Siricoidea of some authors 

 and Xylophaga of others). Of later years they have been treated as 

 a group of equal value with the siricids and tenthredinids. Mac- 

 Gillivray (1906, p. 648) and Enslui (1911, p. 438) treated the group 

 as a family, while Roliwer (1911, p. 217) considers it to be a super- 

 familj^. With the Siricoidea the Oryssoidea show relationship in the 

 habits (being internal feeders in wood), the complete separation of 

 48702°— Proc.N.M.vol.43— 12 10 



Fig. 5. — Abdomen of Oeyssus. (a) Doksal 



view; (6) LATERAL VIEW FROM THE SECOND. 



