1910.] 201 



sweeping in that prolific place Stoke Wood 17/4/07, but the male has 

 the eiid of the abdomen injiu'ed, and it is only by the approximated 

 supra-antennal bristles, the thickened fore tarsi, and bristly pleui-ae that 

 it can be confidently referred to this species. The colour of the 

 halteres is usually so constant, that it comes as a surprise to find it 

 variable here, the variability as in the few other instances of its 

 occurrence being independent of sex. 



Simplex. — An indoor insect, common on the windows here in the 

 autumn, but rare at Newmarket. Whilst quite distinct from the 

 preceding species, from which the slender (normal) fore tarsi and other 

 characters readily differentiate it, it bears a close resemblance to 

 exigua, a species which also is a frequent visitor of our houses in the 

 autumn. Here, however, the bristly nature of the pleurae in the one 

 insect and their bareness in the other, apart from some smaller and 

 less important distinctions, amply separate them. 



Clavipes. — A deep black and abimdant species, occurring in May 

 and again in the aiitumn ; probably also of wide distribution, for 

 Mr. Collin takes it freely on his side the country. Its most obvious 

 features are the limpid wings with their long costal fringe and crowded 

 thick veins, deep costal cells and clubbed hind tibiae, and strongly 

 bristled pleurae. Among my material are two males which vary from 

 the type by having a shorter costal ciliation, but as there are no other 

 differences, they are doubtless nothing more than a variety. With 

 better claim, however, to specific rank is a form which has been chiefly 

 taken by Mr. Collin at Newmarket. In this the palpi are yellowish 

 rather than black and the hypopygium appears different. But these 

 are its only peculiarities, and for the present I j)i"efer to look upon it 

 as a variety. The male hypopygium is unquestionably a character of 

 the highest importance, yet there is often a difficulty over the details. 

 The very smallness of the parts handicaps one greatly, moreover the 

 position may be unfavourable for examination, or other parts, as the 

 legs, may get in the way, whilst the organ itself wears a very different 

 aspect according as the inner parts are exposed or not. Hence caution 

 is needed when dealing with species that measure so little as 1 mm. 



Maura. — This is another of those insects that are fond of entering 

 the house. It makes its appearance in the autmnn and again in 

 smaller numbers in the spring, doubtless after hibernation. Its large 

 size, bare plem-ae and black halteres, the massing of the thick veins at 

 the end of the costa, and the strong and sparse tibial cilia are the 

 salient points about it. 



