APPENDIX. 379 



aviculariiim behind the outer edge^ superiorly. Vibracula 

 very large : setae serrated. 



Hab. — Off Cumberland Islands, 27 fathoms fine grey 

 mud. 



Colour white or yellowish; forms close rounded tufts 

 2|^ to 3 inches in height and width, composed of uniform 

 dichotomously divided branches, about J of an inch wide, 

 and which become ^Wder towards their truncate extre- 

 mities. The ^ibracula are very large, and though dis- 

 tinctly defined, are yet sufficiently transparent to allow a 

 view of the lozenge shaped cells. The central rows of 

 cells vary in number from two to five, and the cells com- 

 posing them are ai'ranged with extreme regularity. The 

 marginal rows are placed in a plane posterior to the 

 central, and as above noticed, the cells of which they are 

 composed are ^ddely different from the central. 



The only other species with which the present can be 

 confounded is Caberea Hookeri [Cellularia Hookerij 

 Fleming) a British form. The latter species appears to 

 differ from C, Lata, chiefly in its having a large tubular 

 spine on each side of the mouth of the lateral cells, and 

 in each of the central cells, or nearly so, being fui'nished 

 with an anterior avicularium, below the opening and to 

 one side. The lateral sessile avicularium on the marginal 

 cells is also much larger. 



Fam. 5. FLUSTRAD^. 



Polyzoarium expanded, continuous or encrusting. Cells 



disposed in straight series, wliich do not radiate from a 



centre. 



17. Flustra, Linn. 



a. Cells on one side only. 



1. F. pyriformis?, Lamoui'oux. 



Cells pyriform, or barrel-shaped, prominent, marked 

 with transverse wrinkles. Ovicells lofty, keeled in front, 

 with a strong central, and two lateral longitudinal ribs. 



