236 Benj. D. Walsh on the Insects inhabiting the Galls 



above aud below, is of a much more horny consistence than the true 

 ventral joiuts. And to carry out his error the more plausibly he figures 

 the ventral joints as dislocated from the dorsal joints. (Jntrod. II, p. 

 138, fig. 8, and p. 139.) Whereas, we have but to recur to Nature to 

 see that his so-called 7th ventral (the true 6th) is not dislocated from. 

 but lies exactly opposite to the 6th dorsal ; his so-called 6th ventral 

 (the true 5th) is not dislocated from, but lies exactly opposite to the 

 5th dorsal; and so on till we come to his so-called 2nd ventral, (the 

 true 1st,) which lies with its tip opposite to the tip of the 1st dorsal, 

 and in Pimpla is pretty long, but in such genera as have a moderate 

 or a long peduncle (Cryptus, Ophion, &c.) is moderate or short. It 

 may be added, that throughout Ichneumon id 'se precisely as in Tenthre- 

 dinidse, the dorsal joints 1 — 7 bear a spiracle % 9 on their lateral sur- 

 face. 



In one word in Ichneumon id se the $ venter is invariably 6-jointed, 

 with its joints corresponding with joints 1 — 6 of the dorsum, while on 

 the contrary the % venter is invariably 8-jointed, although in many 

 genera the two terminal joints are more or less retracted, or overlapped 

 and concealed by the "lateral plates" of the terminal joints of the dor- 

 sum. Hence in species with a very short ovipositor, if we can count 

 the ventral joints we can always distinguish the sex, and if there are 

 more than 6 of them visible the specimen must be % . Of course, care 

 must be taken not to count ventral joint 1 as two joints. 



I have dwelt at perhaps undue length upon these points, because 

 they are not only in themselves of theoretical importance, but in De- 

 scriptive Entomology it is of real practical moment, when it is stated 

 that such and such abdominal joints are colored differently from the 

 rest, to know which particular joints are designated by the describer 

 as being thus colored. What Westwood and Norton consider as part 

 of the metathorax in Tenthredinidx, other writers call the 1st joint of 

 the abdominal dorsum; and what Norton generally calls the 2nd joint 

 of the abdomen Westwood calls the first. For my own part, I agree 

 with Westwood throughout upon this matter. There has been a simi- 

 lar confusion in Pseudoneuroptera, where in Odonata and Ephemeri- 

 dse some authors have described the abdomen as 10-jointed and some 

 as 9-jointed; the truth being, as I have pointed out, (Proc. &c. II, pp. 

 190 — 1,) that the so-called 1st joint of the 10-jointed abdomen is in 

 these two families really metathoracic. Moreover, in those Ichneumo- 

 nidous genera that have very short ovipositors, authors have long re- 

 cognised the difficulty of distinguishing the sexes; and I know of no 



