PLATE VI. 

 Tethys cervina Dall and Simpson 



Fig. 31. Alimentary canal from below. The convolutions of the 

 intestine are shown in their natural position, the liver 

 having been dissected away, e., lower end of the 

 esophagus; ingl., ingluvies, or first stomach; m. st., 

 muscular band of second, or grinding stomach; j st., 

 third stomach; h. coe., hepatic coecum; int., intestine. 



x 3- 



Fig. 32. Relations of hepatic coecum and bile chamber. The 

 wall of the lower portion of the third stomach and the 

 first portion of the intestine have been cut away, show- 

 ing the entrance of the large ducts of the liver in the 

 opposite wall. The substance of the liver itself, which 

 here almost entirely incloses the alimentary canal, has 

 been dissected away. h. coe., hepatic coecum ; /. r., the 

 prolongation into the intestine as a longitudinal ridge 

 of one of the folds in the wall of the hepatic coecum. 



*5- 



Fig. 33. Reproductive system seen from below, the right border 

 being above and to the left. ov. t., ovotestis ; sm. h. d., 

 small hermaphroditic duct; sp. c., spermatocyst ; d. c., 

 duct of Cuvier; sp. p., spiral portion of genital duct; 

 c. p., convoluted portion of genital duct; ov. sp. d., ovo- 

 spermatic duct ; cop. d., copulatory duct ; spth., sperma- 

 totheca; d. spth., its duct; in., flap of the integument, 

 upon the external face of which lies the vulvar aperture ; 

 g. g., genital ganglion; /. v. 3., third nerve from left 

 visceral ganglion, x 8. 



