Sarcophaga. 167 



well known tessellation of pale and black, shifting according to 

 view, though in some species a little more constant; a black middle 

 line is somewhat pronounced. The characters otherwise used are the 

 breadth of the frons, the presence or absence of outer vertical bristles 

 in male, the development of the bristles on cheeks and the length 

 of the third antennal joint. On thorax the number of postsutural 

 dorsocentrals, the presence or absence of præsutural and præscutellar 

 acrostichals, and in the male the presence or absence of apical bristles 

 on scutellum. On abdomen the presence or absence of a pair of mar- 

 ginal bristles on third segment, and the hairs being short and decum- 

 bent or longer and erect on fourth sternite. It must be remembered 

 that all the characters from the bristles may sometimes be liable 

 to individual variation. On the legs the presence or absence in male 

 of a posteroventral comb apically on middle tibiæ, and presence or 

 absence of an anteroventral row of bristles on hind femora; the 

 fringes on posterior tibiæ were mentioned above. On the wings the 

 subcostal vein bare or bristly (though also this character may vary 

 individually, but rarely, at all events in Danish species), and the rela- 

 tive length of third and fifth costal segment. — As said the most 

 important characters lie in the male genitalia; the shape of the 

 fifth sternite and the hairiness of its lamellæ; the marginal hairs on 

 the lamellæ; present along the inner margin and at end, may be short 

 or long and more or less dense, and be developed into strong bristles; 

 often a part of the ventral side of the lamellæ is covered with short, 

 strong bristles, and this is termed a brush. The præhypopygial seg- 

 ment is large, it is generally black and shining, very rarely more 

 or less reddish basally or red; sometimes it is covered with greyish 

 or brownish pruinosity, either all over or as a spot at hind margin. 

 It is generally densely long-haired, either uniformly or there are 

 stronger hindmarginal hairs or bristles. The hypopygium is more 

 or less short or more elongated; it is black and shining or sometimes 

 red; the colour is often a good character, but in some species variable. 

 At the end of the hypopygium the upper and lower forceps are 

 articulated; the shape of the upper forceps gives good characters; the 

 small lower forceps is of less importance. The penis issues below the 

 hypopygium; it consists of a basal portion or shaft and an end part 

 the end of which is generally bent roundly or angularly forwards. 

 At the ventral base of penis issue two pairs of rod-like appendages, 

 the anterior and posterior claspers; often the anterior claspers have 

 shorter or longer hairs behind, and the posterior claspers generally 



