46 Tachinidae. 



segment which wants, the above mentioned more or less rudimentary 

 segment being the sixth and the præhypopygial the eighth. (It is 

 also possible that it is the sixth segment which has disappeared, 

 then the rudimentary would be the seventh)^. The præhypopygial 

 segment may be of various shape and likewise the hypopygium, 

 and this may be of very various size. At the end of the hypopygium 

 are articulated the upper and the lower forceps. The upper forceps 

 generally consists of one piece, often more or less cleft in apical 

 part, or longer up, and sometimes divided into two. The arms of the 

 lower forceps, lying to each side of the upper, are of manifold shape 

 and size, more or less developed, sometimes only present as small 

 pieces as in Sarcophaga. The penis (in widest sense) with its appen- 

 dages issues below hypopygium; it is of very various shape and of 

 much complicated structure (se f. inst. Mueller, Arch. f. Naturgesch. 

 88, 1922, A, 2, 45); at its base generally two pairs of more or less 

 hook-like rods are present, the anterior and posterior claspers. The 

 hypopygium with all its appendages lies at the end of abdomen 

 and is generally bent in ventrally and more or less hidden. The fifth 

 sternite is of a special shape, more or less deeply incised or cleft in 

 the apical margin, often to or near to base, and sometimes its side- 

 lamellæ are drawn out into long processes. In the female the abdomen 

 also generally shows only four visible segments seen from above, 

 the rest being simply drawn in telescopically, but often, however, 

 of special structure, and sometimes, namely in the Phasiinae, they 

 are specially shaped for holding or piercing the host at the oviposition, 

 and here also the otlier abdominal segments may show structures 

 for the same purpose. The second abdominal tergite nearly always 

 has an excavation behind scutellum, which may be smaller or larger, 



Senior White (Record of Ind. Mus. XXVI, 1924, 209) comes to another result 

 as he supposes a first quite membraneous segment, without spiracles and 

 partially fused with thorax; the other segments he has as above. He gets 

 thus, like I, ten segments, but without any disappeared. (He takes the upper 

 forceps as belonging to the otherwise rudimentary tenth segment). But the 

 difficulty is not surmounted herewith, for if we suppose a first segment, 

 anterior to the rudimentary spiracle-bearing one — and theoretically this 

 is possible — then we should come to eleven segments, the original number 

 of urites in Insects. The author states that his second segment is the bare 

 basal part of his third; this is certainly not correct, all that he figures 

 (PI. XVIII, fig. 1) as second and third segment is no doubt only one segment, 

 except just the part with the first spiracle, this, as stated above, often lying 

 in a separate small plate. 



