ZOOLOGY. £45 



6. Salpa. Body not affixed, with two apertures^ one at each 



extremity. 



7. Dagysia. Body tubular, not affixed, angular, open at 



each end. 



** Mouth situated before. 



8. Pterotrachea. Body pervious, gelatinous, with a move- 



able ^« at the head or tail. 



9. Derris, jBo^/^/ round, tapering, jointed ; /eeJer* two. 

 *** Mouth situated before ; body with a lutercd perforation. 



10. Limax. Slug. Feelers four ; vent common with the 



lateral pore. 



11. Laplysia. Feelers ionr ; uew^ placed above the lower 

 extremity. 



12. Doris. Feelers two ; vent as the last genus. 



13. Tethys. Uorfy with two small jaores on the left side. 



**** Mouth before; body surrounded with feelers on the 



fore part. 



14. Holothuria. Feelers or tentacula fleshy, numerous, at 

 one extremity surrounding the mouth. 



1 5. Terebella. Feelers or tentacula capillary, ciliated, sur- 



B 3 



