316 Prof, Westwoocl on the supjiosed abnormal 



females, head downwards, begin hj bending the abdo- 

 men downward, and placing the tip of the ovipositor on 

 the straw at right angles with the body, when the abdo- 

 men resumes its natural position, and the ovipositor is 

 gradually worked into the plant to its full extent. With 

 the aid of a good lens, and by pulling up the plants on 

 which they were at work (which did not appear to dis- 

 concert them in the least) I could view the whole opera- 

 tion." 



Mr. Walsh adds that upon July 3rd he examined " a 

 large lot of the green barley-galls received from Mr. 

 Pettit, and found the larva of the joint fly almost half 

 grown, that is, from 0*004 to 0'006 inch long, and about 

 five times as long as wide. In these green galls, upon 

 the most careful search, he could find no gall-gnat larvae, 

 nor any vestiges of such larvae." If the so-called joint- 

 worm fiy were really a parasite, we must certainly have 

 discovered, at the early period of the year, a few speci- 

 mens of the larvae upon which it was parasitic, or at all 

 events some traces of their handiwork." Mr, Walsh 

 therefore comes to the inevitable conclusion (already 

 arrived at by Harris and Fitch, and contrary to the 

 opinion which Walsh had expressed previously in the 

 ' Practical Entomologist,' i., pp. 10 — 12 and 37, 38) 

 "that the joint fiy was the real author of these galls, 

 and we think it right to bear this public testimony to the 

 correctness of their entomological inferences " (p. 151). 



Mr. Walsh then describes a truly parasitic Chalci- 

 dideous insect {Semiotdlns chakidiphagus) , one of the larvae 

 of which " emerged under our very eyes from the body 

 of a joint worm " ; whilst in other instances he had found 

 the parasitic larvae attached externally to its victim, in 

 the manner common with the larvae of many Cludcis 

 flies. He then details his observations on many speci- 

 mens of the /. liordei, which he had reared from Canada 

 barley-galls, proving that Dr. Fitch's four species of 

 joint- worm flies are mere varieties of one and the same 

 species. 



Adopting an opinion expressed by Professor Agassiz* 

 ('Essay on Classification,' p. 59), Mr. Walsh insists on 



^- " The more I learn upon this subject," says Agassiz, " the more 

 am I struck with the simihirity in the very movements, the general 

 habits, and even the intonation of the voices of animals belonging 

 to the same family." 



