March, 1876.] 217 



Legs furnished with numerous spines and haii's. Feet with large 

 pulvilli and claws ; the points of the latter are mostly broken off on 

 tlie fore, and often on the middle, feet of the males. 



The genus Snrcojyhaga, which includes a considerable number of 

 British species (I have already determined twenty, and have no doubt 

 that many more will be found), is composed of a series of yellowish or 

 whitish-grey flies, striped and variegated with brown or bluish-black. 

 The palpi and antenna; are always black ; the thorax is marked with 

 three longitudinal broad black stripes upon the dorsum, and also with 

 some short and broken lines upon the sides; the abdomen is tessellated 

 upon its upper surface, with a number of irregularly shaped black and 

 white spots, forming glittering patches, which reflect the light, so that 

 they appear of different sizes, shapes, and colours, when viewed in 

 different directions, but are arranged more or less in longitudinal rows 

 or stripes, which are much more distinct in some species than in others. 



The majority of these flies are so much alike, that it is impossible 

 to distinguish the separate species from each other by mere differences 

 in colour and design ; and the greater number of authors having 

 chiefly relied upon these points, very few of the species descx'ibed by 

 them cau be determined with certainty. Varieties of the same have 

 been named as separate species, different species have been confounded 

 together, and the same species has been described by different authors 

 under different names. Though so much alike, however, in general 

 appearance, many very good structural points exist by which the dif- 

 ferent species of Sarcophaga may be separated from one another, and 

 named with certainty ; and, before commencing the description of 

 them, I will briefly enumerate the principal distinctive characters upon 

 which reliance may be placed. 



Thiijirst, which has been noticed by all authors, and by which the 

 species may be separated into two principal divisions, is llie colour of 

 the terminal segment of the abdomen, which is always black or grey 

 in one division, and red in the other. 



The second important character is the presence or absence of 

 minute spines upon the second longitudinal vein of the wings, similar 

 to those present in all species at the base of the fourth. 



The third is whether the hind tibia) of the males are bearded or 

 not with long soft and often thick hairs. 



T^\\(i fourth is whether the second alnlnminal segment is armed like 

 the third with two strong central spines upon its posterior miirgin. 



Thoffth is the number of bristles in the two Idugitudinal rows 



