280 BRUES. 



halfway to the tip and the apical one to the tip where it meets the tip 

 of the ventral one. Between these the ovipositor issues. It is very 

 short and its basal attachment lies well within the last segment. Its 

 valves are heavy and lie one on each side, meeting on the median line 

 above and below. Many Belytids are parasitic on dipterous larvse in 

 fungi and quite probably the Scorpiotelei is modified to reach its host 

 in some tube-bearing fungus such as Boletus or Polyporus. ^ In cer- 

 tain other Belytids, e.g., Miota, the tip of the abdomen is upturned and 

 more or less plowshare-shaped, but does not exhibit such excessive 

 elongation. 



The Platygastrid genus Inostemma is characterized by a most 

 remarkable projection which arises from the dorsum of the first 

 abdominal segment and extends forward over the thorax with its tip 

 over the anterior ocellus. The curvature of this horn corresponds 

 closely to that of the mesonotum, above the surface of which it is 

 raised, and the vertex of the head bears a median depression to allow 

 free motion of the head without interference by the tip of the horn. 

 This rigid process is present only in the female and although several 

 entomologists had suggested that it received the ovipositor, its func- 

 tion remained in doubt till Marchal ('06) showed that in the European 

 Inostemma piricola, it really serves to receive the basal portion of the 

 ovipositor which is much longer than the abdomen, so that when not 

 extruded the base lies in the anterior part of the horn. The Inostemma 

 studied by Marchal deposits its eggs in a Cecidomyiid larva which 

 feeds within the small developing fruits of the pear. An examination 

 of the North American Inostemma liorni Ashm. shows that, as might 

 be expected, the mechanism of the oviposition is entirely similar to 

 that of the European species. Marchal was at a loss to account for 

 the apparent origin of the ovipositor within the basal tergite of the 

 abdomen. Unfortunately the only specimens available have been 

 mounted dry for a number of years, but dissections of these which I 

 have made show that the ovipositor appears actually to arise within a 

 n^embranous apical segment which has been invaginated so as to 

 occupy the cavity of the process on the first segment. As there are 

 six visible chitinized segments, this membranous tube is no doubt the 

 seventh, or seventh and eighth abdominal segments and it must 

 furnish the muscular apparatus for the manipulation of the ovipositor. 

 The horn is therefore only secondarily a housing for the ovipositor. 



1 The Australian genus Stylaclista Dodd ('15) is evidently very similar to 

 Scorpioteleia, having the third to sixth abdominal segments produced into a 

 long fleshy stylus. 



