106 [ Ma y. 



insect which occurs on the bants of the Thames between Putney and 

 Kew is regarded by Capt. Deville as a variety 



13, Oppidans Road, N.W. : 



April 9th, 1914. 



SOME OBSERVATIONS ON THE SPECIFIC CHARACTERS 

 Of HOMALOTA (BESSOBIA) OCCULTA, AND H. FUNGIVORA, &C. 



BY J. H. KEYS, F.E.S. 



During October and the early part of November last, I obtained 

 18 male and 27 female specimens of H. fungivora, Th.,from dead birds 

 set as traps in a garden at Yelverton, South Devon. Two males and 

 three females of H. occulta, Er., and three of each sex of H. monticola, 

 Th., were also taken. In addition I possessed a few examples in 

 my collection. With this considerable amount of material it seemed 

 desirable to examine the species, with especial reference to the females 

 of occulta and Jungivora, as neither Fowler nor Ganglbauer describes 

 the latter form, and the recently published synopsis of the tribe by 

 Cameron (Trans. Ent. Soc. Lond., 1913, p. 301) also lacks details of it. 

 However, Thomson's description is given in Mulsant and Eey's 

 Myrmedoniaires, Pt, II, p. 139, namely that the 7th (i.e., the 8th) 

 dorsal segment is simple and rounded. My specimens agreed with 

 this description, and an additional character which I discovered in the 

 9th segment and have recorded below seems quite confirmatory of this 

 distinction for fungivora, in contrast to the emarginate 8th segment in 

 occulta, female. In occulta, male, the formation of the posterior raised 

 line of the 8th segment (Fig. 1) appears to me to be different in 

 character from that of male fungivora, and suggests a geometrical 

 pattern formed by two arcs of circles joined end to end. That of 

 fungivora may be nearly straight across and more or less indefinitely 

 notched in the centre, or may be varied in form as sketched 

 below. Indeed I observed so great a variation in the configuration 

 of these lines in the examples under notice (Figs. 2 — 6), — in some 

 cases distinct clear-cut notches being present in the middle thereof, — 

 that I suspected the possibility of another species being mixed with 

 them. However, on extracting the genitalia (Fig. 10) of many speci- 

 mens selected for their diversity in the point in question, I could detect 

 no differences in their structure. It therefore seems that the species 

 is variable to a very interesting degree in its secondary male characters. 

 The genitalia of occulta, (Fig.- 9) are quite unlike those of the last 



