SERTULARIA. 49 



-Sea-thread Coralline. Ellis Corallin. pag. 21. tab. 12. 

 No. 18. fig. a. c. A. C. 



Sertularia dichotoma. Linn. Syft. Nat. Ed. 12. p. 131 2. 



It is found on the Suffex coaft, but in greater plenty 

 on the coaft of Holland. 



20. Sertularia geniculata. Knotted Sea-thread Coralline, 



Sertularia denticulis al- This Coralline has alternate 



ternis calyciformibus^ pe- cup-fhaped denticles, with 



dunculis contortis, ovariis twifted ftalks ; the ovaries are 



ovato-truncatis axillari- oval, and flattifh at top. 

 bus. 



Knotted Sea-thread Coralline. Ellis Phil. Tranf. Vol. 

 48. tab. 22. fig. 1. Corallin. pag. 22. tab. 12. No. 19. 

 fig. b. B. 



Sertularia geniculata. Linn. Syft. Nat. Ed. 12. p. 1 3 1 2. 



This creeping little Coralline has but few branches, 

 and they are alternate : it is found adhering by little tubes 

 to the podded Fucus, and fometimes to the Sea-Oak 

 Fucus. I have met with it on the coaft of Suffex, grow- 

 ing upon the Afcidia inteftinalis of Linn. Syft. . Nat, 

 Ed. 12. p. 1087. which is a foft, white, membranaceous 

 animal, nearly egg-fhaped, that fixes itfelf by its bafe to 

 rocks and fhells ; has two openings, one at the top and 

 the other a little lower, from whence it fquirts out the 

 water. On this the Knotted Sea-thread Sertularia, or 

 Coralline, fends forth its root-like tubes, nearly in ftrait 

 lines ; from whence arife, at a fmall diftance from each 

 other, young fprigs about an inch high, properly fur- 

 ruihed with their denticles and polype-heads, fo as to 



H form 



