MARINE POLYZOA. 13 



eal eminences. A few scattered papillae on the surface of the 

 sides and back. Ovicelligerous cells gemmate. 



Catenicella carinata, Busk, Voy. of Rattlesn. i. 363. 

 Hab. Bass' Strait, 45 fathoms. 



This remarkable form differs so widely in many respects from 

 any of its congeners, as almost to deserve to be considered as the 

 type of a distinct subgenus. The lateral processes, which may 

 be taken to represent the perfect avicularia of the other species, 

 are, as far as can be ascertained from specimens that have been 

 dried, without a moveable mandible, and are probably really so 

 because there is no corresponding beak. These processes are 

 channelled in front nearly from the base to the extremity ; they 

 arise by a broad base on each side of the mouth and on the front 

 of the cell, and from the conjoined bases is continued upwards 

 and downwards, or to the top and bottom of the cell, a promi- 

 nent flattened band. The expanded bases circumscribe an oval 

 space nearly in the centre of the front of the cell, the upper 

 two-thirds of which space are occupied by the circular mouth, 

 on each side of which is a small calcareous tooth, to which appa- 

 rently are articulated the horns of the semilunar labial cartilage. 

 The lower third is filled up by a yellow horny ? membrane, upon 

 which are placed three conical eminences disposed in a triangular 

 manner. The back of the cell is very convex, and has, running 

 along the middle of it, an elevated crest or keel, acuminate 

 in the middle. The ovicell is situated in front of the cell below 

 the mouth, and below it are three considerable-sized areolated 

 spots, disposed like the three conical spines in a triangle. The 

 cells upon which the ovicells are placed, are always geminate, 

 that is to say, have a smaller cell growing out from one side. It 

 is not improbable that the ovicelligerous cell in fact represents 

 two cells, to the lower one of which the ovicell properly belongs. 



2. ALYSIDIUM. 



Cells connected by short corneous tubes, of which two arise 

 from a single cell, at each bifurcation. Avicularia single and 

 anterior, or double and lateral, or altogether wanting ? 



Alysidium, BusJc, MSS. 



Closely allied to Catenicella ; the difference in the mode in 

 which the branches are given off, appears to afford a sufficient 

 ground for the separation from that genus, of the forms included 

 in the present. It must be stated, however, that there is, except 

 in that respect, but little connection between the two species here 

 somewhat arbitrarily made congenerous, each of which will most 

 probably form the type of a distinct genus. 



