1920] Seamans: Anatomy of A nthomyia 209" 



Immediately below the scutellum is an exceedingly convex 

 sclerite, part of the post-scutellum, which extends laterally to 

 the pleurotergite, and is known as the mediotergite (mdtg). 

 Below the mediotergite is a sclerite which beai;s the halteres, the 

 metanotum (mtn). Back of the meropleurite is a long, slender 

 sclerite in an oblique position, the metaepisternum, which is 

 divided at the upper end by a suture making two divisions in it. 

 Below the metanotum and posterior to the metaepisternum is a 

 sclerite of similar shape, the meta-epimeron (mtem) (Fig. 12). 

 Surrounded by the metaepisternum, the pleurotergite and the 

 meropleurite is the posterior spiracle (spp) (Fig. 17). 



There are membranous portions of the thorax near the base 

 of the wings, which allow freedom of movement of parts. There 

 are four small plates or sclerites in this membranous portion, 

 two at the base of the wings, and two posterior and above the 

 ptero-pleurite. The first two are the basal plates (bpl) and the 

 latter are the sub-alar plates (sapl). Above the sub-alar plates 

 is a triangular, more or less distinct, region extending towards 

 the scutellum, known as the juxtascutellum or scutellar 

 bridge, (jscl). 



The chaetotaxy of the pleura is similar in both sexes with 

 the exception of the sternopleurite. The anepisternum has four 

 stout bristles near its posterior margin and a more or less cov- 

 ering of hair. In the male, the sternopleurite has one strong 

 bristle below the sternopleural suture, one at the posterior 

 angle of the pleural suture, and one just below the last, also 

 along the pleural suture. (Fig. 12). In the females the last 

 mentioned bristle is wanting. In both sexes the sternopleurite 

 has two (more or less strong) bristles on the anterior surface 

 just above the front coxas, and is somewhat covered with hair 

 on the posterior portion, which become bristles just in front of 

 the mesocoxae. The coxal sclerite next to the sternopleurite has 

 a row of four strong bristles. 



Each spiracle is surrounded by fine hairs which curve over 

 the openings and serve as a protection or sieve. 



THORACIC APPENDAGES. 



The wings show no difference of structure in the two sexes. 

 (Fig. 13). The costal vein extends to the tip of the fourth vein, 

 and is weakly pectinate. At the tip of the auxiliary vein, the 

 costa is broken, and a short, weak spine is located at the basal 



