ZOOLOGY. 245 



6. Salpu. 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. Pierotrachea. Body pervious, gelatinous, with a move- 



able ^n at the head or tail. 



9. Derris. Body round, tapering, jointed ; feelers two. 

 *** Mouth situated before ; body zoith a lateral perforation. 



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



lateral pore. 



\ 1 . Laplysia. Feelers four ; vent placed above the lower 

 extremity. 



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



1 3. Tethys. Body with two small pores on the left side, 



**"** Mouth before j body surrounded mth feelers on the 

 fore part. 



1 4. Ilolothuria. Feelers or teutacula fleshy, numerous, at 

 one extremity surrounding the mouth. 



15. Terebella. Fee/er* or tentacula capillary, ciliated, sur- 



E 3 



