Plate III. 

 Figs. 9-14, Tethys dactylomela (Rang). 



Fig. 9. Buccal ganglia in situ, seen obliquely from below and 

 the right side, es., cut end of esophagus ; s. gl., right 

 salivary gland, its severed distal end bent forward and 

 to the right ; h%ic. g., buccal ganglia ; c. h. con., cerebro- 

 buccal connective. The buccal nerves are numbered 

 serially from i to 6. In this specimen the 5th and 6th 

 nerves arose from a common trunk, x 8. 



Fig. 10. Buccal ganglia, ventro-posterior face. Lettering as in 

 Fig. 9. X 8. 



Fig. II. Buccal ganglia, dorso-anterior face. Lettering as in 

 Fig. 9. X 8. 



Fig. 12 Posterior margin of labial armature showing outlines 

 of bases of the rodlets. x 223. 



Fig. 13. Two elements of the labial armature from anterior 

 margin of plate, x 137. 



Fig. 14. Parieto-visceral ganglion complex, r. p. g., right parie- 

 tal ganglion; /. v. g., left visceral ganglion; pi. par. 

 con., right pleuro-parietal connective; pi. v. con., left 

 pleuro-visceral connective; r. p. i., ist parietal, or vulvar 

 nerve; la., its branch forming an anastomosis with the 

 branch of the 3rd pedal nerve supplying the Organ of 

 Bohadsch ; r. p. 2, second parietal, or osphradio-ctenidial 

 nerve ; /. v. i, first visceral nerve to vesicle of Swammer- 

 dam, the spermatocyst ; /. v. 2, second visceral nerve; 

 /. V. ^a., and /. v. j^., the two main branches of the 

 third visceral nerve, in some specimens arising as dis- 

 tinct nerves, in others branching from a common trunk. 

 x8. 



Figs. 15-22, Tethys cervina Dall and Simpson. 



Fig. 15. Outline of labial armature, x 8. 



Fig. 16. Rodlet from anterior portion of labial armature, x 183. 



Fig. 17. Surface view of Organ of Bohadsch, or hypobranchial 



gland, a., artery ; i, nerve from right pedal ganglion ; 



2, nerve from left visceral ganglion, x 6. 



