392 EXPLANATION OF THE PLATES. 

 Fig- 



12. Maxilla of Lithotrya Phodiopus. 



13. ,, Pollicipes polymer us. 



14. „ „ mitella. 



15. „ Pcecilasma eburnea. 



16. Outer maxilla of Conchoderma virgata ; {a), orifice 



of the olfactory cavity, the inner 

 delicate chitine membrane of 

 which is seen within, the spe- 

 cimen having been treated with 

 caustic potash. 



17. „ „ Pollicipes mitetta, showing the 



two principal muscles, and the 

 prominent, tubular, (6) olfactory 

 orifices. 



18. Caudal appendages, and basal segments of the sixth 



pair of cirri, of Lepas anatifera ; (a), anus; (b), 

 caudal appendages ; (c), lower segment of pedicel 

 of sixth cirrus ; (d), upper segment of ditto ; {e), 

 basal segments of the two rami. 



19. Caudal appendage (right-hand side) of Pollicipes sertus. 



20. „ „ ?J Scalp ellum Pero?iii. 



21. ,. „ „ Scalpellum vulgare. 



22. ,, „ „ Pollicipes cornucopia. 



23. „ „ (left-hand) Lithotrya dorsalis; (a), 



caudal appendage; (c), lower 

 segment of pedicel of sixth 

 cirrus ; (d)> upper segment of 

 ditto ; {e), segments of one of 

 the rami. 



24. Portion of caudal appendage of Lithotrya dorsalis, 



highly magnified. 



25. Pollicipes polymer us ; anterior ramus of the second 



cirrus. 



26. Lepas anatifera; a segment of the sixth cirrus, showing 



the arrangement of the spines ; (a), main anterior 



