322 Prof. Westwoocl on the su/pposed abnormal 



European Isosoma linearis which was bred from wheat 

 by Dr. Giraud,* who considered it inquilinous in the 

 swellings formed by the dipterous Octhiphila polystigma 

 of Meigen. Kaltenbach remarks, however, that although 

 obtaining the Isosoma many times from the wheat, he 

 never succeeded in seeing this dipteron — a very suggestive 

 fact." 



The attention of the members of the Scientific Com- 

 mittee of the Horticultural Society of London was directed 

 by Mr. Bateman, on the 2nd March, 18G9, to the injury 

 committed by several insects on the bud of an exotic 

 species of Orchid, beneath the overlapping leaves of 

 which two white fleshy grub-like larvae (evidently Curcu- 

 lionideous, and closely resembling those of the common 

 nut weevil) were securely nestled, and which had been 

 feeding upon the thickened substance of the leaves, the 

 surface of which was eaten off to some distance without 

 any hole being gnawed through the leaf. Immediately 

 in the vicinity of these larvset were also found several 

 minute dead pupae lying in a mass of hard dry particles 

 of dark-coloured matter (doubtless the excrement of the 

 larvae from which the pupae had been developed). These 

 pupae were Hymenopterous, and by carefully scaling off 

 the thin horny external pellicle under the microscope 

 they were ascertained to belong to the family Chalciclidce 

 and to the genus Isosoma, both sexes of which were thus 

 brought to life. In this case it was evident, 1st, that 

 the weevil larvae were uninjured, so that the Isosomce 

 were not parasitic upon them ; 2nd, that the Isosomce 

 larvae had already gone through the whole process of 

 their econom}', whether phytophagous or entomophagous ; 

 and 8rd, as no trace could be perceived of a third species 

 of insect, the probability seems evident that the Isosomce 

 were not parasitic on other insects. For the sake of 

 identification I proposed the name oilsosoma orchidearam 

 for this species {,' Gardeners' Chronicle,' 27th Nov., 1869, 

 p. 230). 



The following is a description of the species : — 



* The important memoir of Dr. Giraud (' sur les Insectes qui 

 vivent sur le Roseau commun ') will be noticed in a supplementary 

 article at the end of the present volume. 



]■ It might be assumed, from the presence of the weevil larvae 

 and parasitic pupae in the same burrow, that the latter were para- 

 sitic upon the former ; but it will be perceived that the larvae were 

 still well and active, whilst the parasites had already completed 

 the larva period of their lives and had become pupae. 



