Plate X. 

 Tethys cervina Dall and Simpson. 



Fig. 40. Dorsal view of shell, x 46. 



Fig. 41. Outline sketch of preserved specimen in dorsal view, 

 mainly intended to show the general proportions and 

 the markings surrounding the mantle pore. Tentacles 

 and rhinophores strongly contracted, the head itself 

 less so. X 2. 



Fig. 42. Detail of parieto-visceral ganglion complex from above, 

 the two fused ganglia being rotated into side view, and 

 all the nerves being more or less displaced to show 

 their mutual relations, pi. p. con., pleuro-parietal con- 

 nective; pi. V. con., pleuro-visceral connective; r. p. g., 

 right parietal ganglion; /, v. g., left visceral ganglion; 

 r. p. I, vulvar nerve ; r. p. la., its branch anastomosing 

 with the third pedal nerve; r. p. ib., its branch to an- 

 terior end of large hermaphroditic duct; r. p. 2, os- 

 phradio-ctenidial nerve; osp. g., osphradial ganglion 

 together with a portion of the integument cut out from 

 the body wall ; ct. g., ctenidial ganglion ; osp. g. i, 

 nerve to anterior and lateral regions of the mantle; 

 ct. n., main ctenidial nerve; /. v, i, nerve to vesicle of 

 Swammerdam, or spermatocyst, and its duct; I. v. 2, 

 I. V. J, /. V. 4, second, third and fourth nerves from the 

 left visceral ganglion, x 20. 



