ZOOLOGY. 245 



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. Pterotrackea. Bodij pervious, gelatinous, with a move- 



able Jin at the head or tail. 



9. Derris, jSat/^ round, tapering, jointed • /eeJer^ two« 



Mouth situated before ; bodif with a lateral perf or ation» 



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

 lateral pore, 



11. Laplysia. Feelers four ; z?e;2^ placed above the lower 

 extremity. 



12. Doris. Feelers two ; v^jit as the last genus. 



13. Tethijs. Bod^ with two sma\\ pores on the left side. 



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

 fore part, 



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

 one extremity surrounding the mouth. 



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



a 3 



