PLATE X. 



Figs. 1-5/ Octacntmus hythius, Moseley. 

 Figs. 6-18. OctacnemuH sp. (?). 



.-.(//. Subneural gland. 

 1.0. Sense organ. 

 St. Stomach. 

 t. Test 



t'. Thickened test, 

 tes. Testis. 

 m.sc. Visceral mass. 



Fig. 1. 



Fi2. 



2. 

 3. 

 4. 



5. 



Fig. 6. 



Fig. 7. 



Fig. 

 Fig. 

 Fig. 



Fig. 8. 

 Fig. 9. 

 Fig. 10. 

 Fig. 11. 

 Fig. 12. 

 Fig. 13. 

 Fig. 14. 

 Fig. 15. 



Fig. 16. 

 Fig. 17. 



Fig. 18. 



Octacnemus hythius, Moseley, from tlie lower surface ; natural size. 



The same from the upper surface ; natural size. 



Visceral mass of same ; enlarged. 



Nerve ganglion, &c., of same; magnified. 



Arrangement of some of the muscle bands of the same ; enlarged. 

 Octacnemus sp. (?), from upper (anterior) surface ; natural size. 



Posterior dorsal part of same seen from the side, to show the probable place of 



attachment {ad.), and the projection containing the viscera ; enlarged. 

 Section along one of the conical processes of same ; natural size. 

 Dissection of same, showing the visceral mass, &c. ; natural size. 

 Anterior surface of visceral mass, showing nerve ganglion, &c. ; enlarged. 

 Nerve ganglion and neighbouring parts ; magnified (S. 1). 

 Part of test on upper surface ; highly magnified (S. \). 

 Part of mantle, showing arrangement of the fine muscle bands (S. 1). 

 The arrangement of the larger muscle liands in the conical processes; enlarged. 



Part of the posterior wall of the branchial sac (horizontal membrane) ; magni- 

 fied to show the circular depressions (S. 1). 



Squamous cells covering the general surface of last ; highly magnified (S. \). 

 Cubical cells along edges of the depressions, in surface view ; highly magnified 



(S. i)- 

 Tlie same cells in profile view ; highly magnified (S. \). 



' These figures are from the original drawings, for the use of which I have to thank Professor Moseley. 



