2b SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 94 



2^p. The muscular sheath of the oviducts. — The walls of the median 

 oviduct and of the proximal parts of the lateral ducts have a muscular 

 sheath of internal circular fibers and external longitudinal fibers. The 

 longitudinal fibers are continued upon the walls of the calyces, but the 

 circular fibers appear to be absent in these parts of the lateral ducts, 

 and no muscles are present on the anterior glandular parts. 



MUSCLES OF THE NINTH SEGMENT 



The musculature of the ninth segment differs so much between the 

 male and the female that few muscles can be identified with each other 

 in the two sexes, or homologized with muscles of the pregenital seg- 

 ments. Besides the segmental muscles there are in the female special 

 muscles of the ovipositor, and in the male special muscles of the 

 phallic organs. 



In the male grasshopper the following nine muscles take their origins 

 on the segmental plates of the ninth segment. 



260. Internal dorsal muscle (fig. 12).- — A small band of fibers 

 arising near the mid-dorsal line on the anterior edge of the ninth 

 tergum, the fibers spreading posteriorly and laterally to their insertions 

 on the anterior margin of the tenth tergum. This small muscle is the 

 only representative of the intertergal dorsals in the ninth segment of 

 the male. 



261. Retractor of the phallus. — A short, thick, conical muscle aris- 

 ing by a wide base dorsolaterally on the ninth tergum (fig. 12). in- 

 serted posteriorly and ventrally on a small oval sclerite in the wall of 

 the genital chamber just laterad of the epiphallus (fig. 25 D). 



262. 26J. Muscles of the female not represented in the male. 



264. Ventral dilator of the rectum. — A fan-shaped muscle arising 

 on the ninth sternum at the base of the sternal apodeme (fig. 12 

 shows point of origin), the slender fibers spreading dorsally in a 

 longitudinal plane to their insertions on the ventral wall of the rectum 

 (fig. 16 A). 



263. Ventral muscles (fig. 12). — A pair of straplike muscles on each 

 side arising laterally on the ninth sternum at the base of the anterior 

 apodeme, going posteriorly and dorsally to the membranous venter 

 of the tenth segment just before the base of the paraproct. 



266. Retractor of the aedeagus. — A broad, thin sheet of fibers aris- 

 ing from a median ridge of the ninth sternum (figs. 12, 25 x\), at- 

 tached dorsally to the wall of the genital chamber laterad of the base 

 of the aedeagus (fig. 25 x\). 



267. Protractor of the aedeagus. — A large, triangular muscle aris- 

 ing by a long base on the median ridge of the ninth sternum, mesad 



