1920] Seamans: Anatomy of Anthomyia 213 



The male abdomen (Figs. 37 and 38) differs from the female 

 abdomen (Figs. 40 and 41) in shape, number of segments and 

 form of the ventral plates. In general shape it is oval, the 

 anterior end produced laterally, the posterior end blunt. It is 

 about twice as long as broad and the segments, with the excep- 

 tion of the first and last, are of about equal widths. The female 

 abdomen is about the same size as that of the male, but more 

 pointed posteriorly, the second and fifth segments being the 

 longest. The genital segments are barely visible in both sexes 

 from above, and what appears to be the sixth segment in the 

 male is the first genital segment. This is more apparent from 

 the ventral view. Spiracles (sp) are visible on all five segments 

 when viewed ventrally. 



Ventrally the first segment is indicated by a short, wide 

 ventral plate (vpl) connected to the dorsal sclerite by a mem- 

 brane, the abdominal pleura. The second segment is produced 

 into a ring at its anterior margin. The third and fourth ventral 

 plates in both sexes are simple, rather long, and narrowed 

 slightly posteriorly in the female, but almost square in the 

 male. The fifth ventral plate (vp5) in the female resembles the 

 third and fourth, but the fifth ventral plate of the male is 

 complicated, being produced posteriorly into two long branches 

 between which the forceps and genitalia lie when extended. 



There are two genital segments in the male, the first a con- 

 vex, somewhat ringlike segment, and the second (Fig. 37) is 

 almost completely divided into two lateral halves with the anal 

 opening (ao) between them. From the apical margin two 

 branches project which are the forceps. The genital organs are 

 found in the two genital segments but mostly in the second. 

 (Fig. 32). At the posterior basal portion of the penis (pns) 

 there is a hooklike process, the posterior clasper (cp) (Fig. 33). 

 Opposite to this on the anterior side is located the anterior 

 clasper (ca). 



There is only one genital segment in the female, a small, 

 ring-like segment, with an opening on its ventral surface, 

 which serves as a genital and excretory opening. The genitalia 

 are all internal. 



For the most part the abdomen in both sexes is covered 

 with hair, which is shorter and less dense along the median 

 dorsal line. The first segment in the female has no distinct 

 bristles, while the same segment in the male has a few bristles 



