OTHONIA. 



275 



rowed posteriorly, of a reddish or yellowish-brown colour, stained 

 with the contents of the intestine, annulate ; the rings thirteen in 

 number, smooth, furnished on each side with a small fascicle of 



No. XLVI, — Oihonia Fabricii. 





a. A tuft of Laurentia pinnatifida, with the animal intermixed, natural size. 



b. Worm removed from the tube, natural size. 



c. The same magnified. 



d. Head protruded from the tube, with tentacles displayed, as seen through 



the magnifier. 



e. The same more highly magnified. 



retractile bristles, which can be pointed either forwards or backwards ; 

 the terminal segment semioval, obtuse, marked on each side with a 

 distinct black speck ; bristles bent, and somewhat thickened about 

 the middle, whence they taper to a very sharp point ; first two seg- 

 ments rather narrower than the following ; the anterior with a pro- 

 jectile semioval process on the dorsal aspect, and marked with two 

 round black eyes 1 placed towards the sides ; branchial tentacula 

 one-third the length of the body, straw-colour, unspotted, in two 

 dense tufts originating in the sides of the head, each tuft consisting 

 of three main stalks, which are ciUated with numerous filiform 

 straight filaments, serrulate with very short processes on their inner 

 aspects ; mouth between the tufts ; intestine straight, nearly equal 

 throughout ; the anus terminal ; space between the intestine and 

 sides mottled, transparent. 



Obs. This, although not hitherto enumerated among our natives, is 

 certainly the most common species of its family on our coast. It lives 

 in a narrow cylindrical tube, about twice its own length, placed in 



T 2 



