The sexes of Ophion are rather difficult to distinguish, for 

 even the abdominal appendages are very similar ; but an ob- 

 lique suture, in which the oviduct is secreted, distinguishes the 

 females: this oviduct is short and rigid, being well fitted for 

 puncturing the skins of larvae in order to deposit the eggs ; 

 and from its acuteness and horny substance it seems to be 

 equally well adapted for defence. 



It has struck me as very remarkable that one often can ob- 

 tain only one sex of Ophion from an infested larva, although 

 a considerable number may be hatched : having observed this 

 several times it can scarcely be accidental ; I am therefore rather 

 inclined to think that one sex appears before the other, and 

 that the eggs of each are deposited separately in different 

 Caterpillars. 



The following are British species, 2 of which are unrecorded 

 natives. 



1. O. luteus Linn. — Schccff. Icon. t. \.f. 10. 



" Testaceous, eyes fuscous ; interior nervure of the radial 



cell straight : male 6 — 9,fem. 4 — 9 lines." 

 The maggots are said to infest the larvae of Noctua prcecox 

 (pi. 539.), but I have always obtained the fly from the pupseof 

 Cerura Vinula ; the female I have found in May, and I took a 

 small pair the middle of last October flying amongst heath in 

 the neighbourhood of Heron Court. 



2. merdarius Grav. v. 3. p. 698. 7^". 138. 



" Testaceous, eyes fuscous, interior cell bipunctate in both 

 sexes : 6 to 10 lines long." Grav. 

 I have taken it in Norfolk. 



3. ramidulus Limt. 



" Testaceous, apex of abdomen black ; interior, cell bi- 

 punctate in both sexes : 6 to 10 lines." Grav. 

 I took a specimen in Darent Wood, I believe. 



4. ventricosus Grau. — Curi.B.E.pl. 600, the male a little mag- 

 nified. 



" Rufous, apex of abdomen, pectus and metathorax black 

 or maculated with black : male 4^^ — 7^ lines, y^w. 6^ to 7^." 

 Grav. 

 Beginning of June near Oxfoi'd. 



5. marginatus Jur. tab. 8./. 4. 



" Rufous, apex and base of abdomen, also suture of the 

 thorax black : 7 — 10 lines." Grav. 

 May and June, amongst pine trees. 



The Plant is Heracleum Sphondylium (Common CowParsnepj. 



