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ON A PARASITIC DROSOPHILA FROM TRINIDAD. 



By C. G. Lamb, M.A., B.Sc, 

 Clare College, Cambridge. 



The material for this paper was forwarded to the author by Dr. Guy Marshall, 

 of the Imperial Bureau of Entomology, and was collected by Mr. C. B. Williams. 



The insects were said by him to be parasitic on a Cercopid of the genus Clastoptera, 

 which was found attacking cacao trees. This highly unusual habit gives much 

 interest to the species. Unfortunately the number of individuals sent was quite 

 inadequate to enable one to deal satisfactorily with such small and obscure insects, 

 especially as shrivelling takes place to a different extent in various individuals, which 

 renders the provision of a reasonably large number more necessary than in more 

 normal forms of fly. The individuals sent included three pinned ones of a species 

 from Trinidad (West Indies), and one pinned one of a species from Panama, together 

 with the fragments of two others of the latter species in spirit. In spite of the 

 paucity of material, it was felt to be desirable to put on record as fair a description 

 as could be made under the circumstances. Two of the individuals of the Trinidad 

 species were of one sex, and the third was apparently the other sex of the same 

 species. The two former had all the appearance of representing the male, having 



Fig. 1. Terminal segments of Drosophila paradoxa, $, 



viewed obliquely from below, X 70 ; explanation 



in text. 



brighter eyes, darkened wings, and the general facies of that sex. The genitalia 

 were small and hidden in a terminal hood, such as is found in Drosophila melanogaster 

 and Leucophenga maculata, but it was smaller than in either of these, even than in 

 the latter, in which the hood is only moderately open at the tip, while widely so in 

 the former. In both these species the genitalia can be seen inside the hood, but 

 in the present species only the tips of the fleshy processes are visible. Still, as far 

 as things can be made out without destroying the specimens, they will pass for males. 

 The desirability of having a few spare individuals available for dissection is very 

 great, as otherwise points of this sort have often to be left in some uncertainty. Very 

 little doubt would have been felt on this matter had it not been for the unusual 

 characters possessed by the third specimen. On the lower surface of the abdomen 

 are borne some truly remarkable chitinous hooks ; in fig. 1 is shown a somewhat 

 diagrammatical representation of the terminal segments viewed obliquelv from 

 (C478) E 2 



