CELLEPORID.E : LEPRALIA. 301 



The crust consists of a congeries of egg-shaped cells laid in a single 

 layer, and disposed in regular rows, yet so that the cells of one row 

 are not exactly opposite to those contiguous to it, but advanced one- 

 half of their length forwards ; or, in other words, the apertures of the 

 first row of cells are not on a line with those of the second but with 

 those of the third row ; and this is the normal arrangement of the 

 cells in all the Polyzoa. It is equally general for the Lepraliae to 

 spread out into a circle, but the figure is often deranged by acciden- 

 tal causes, and by irregularities in the site. 



The polype- cell is shaped like a little barrel, and at its first for- 

 mation is always distinctly separate from the adjacent ones, but in 

 some species the cells coalesce and become immersed in the common 

 crust, and hence their true form and character can only be ascer- 

 tained by examining those which occupy the margin of the crust. 

 In other species the aperture, always terminal, is often concealed 

 and distorted by the ovarian capsules, which, like thickly strewed 

 pearls, often roughen the surface of the polypidom. These have 

 been the means of confusing the characters of several species, for some- 

 times the ovary has been described for the cell itself, and sometimes 

 it has been mistaken for a part of the aperture, which has thus 

 ascribed to it a figure that the ovigerous cell only can ever assume. 



* Wall of the cells smooth. 



1. L. HYALINA, cells sulcylindrical, the wall thin, trans- 

 parent and smooth ; the aperture circular, oblique, with an 

 even narrow rim. 



PLATE LIV. FIG. 1. 



Cellcpora hyalina, Lin. Syst. 1286. Fabric. Faun. Grcenl. 435, no. 442. Esper 



Cellep. tab. 1. fig. 1, 2. Lamour. Corall. 38. Dose Vers. iii. 148. Berenicea 



hyalina, HassaU in Ann. and Mag. N. Hist. vii. 367. Lepralia hyalina, W. 



Thompson in Ann. Nat. Hist. v. 253. 

 Var. /3. Wall of the cells thicker, calcareous, and opake. Lepralia cylindrica, 



HassaU in Ann. and Mag. N. Hist. vii. 368, pi. 9, fig. 6. 

 Var. y. Cells heaped, usually opake and calcareous. Cellepora ovoidea, Lamour. 



Corall. 38. pi. 1. fig. 1. Blainv. Actinolog. 444. Lam. Anim. s. Vert. 2de edit. 



ii. 259. Lamour. Expos. Method. 2. tab. 64. fig. 4, 5. D. Chiaie Anim. s. Vert. 



Nap. iii. 38. tab. 34. fig. 33. 



Hob. Parasitical on algse, shells, stones, and corallines." " Com- 

 mon on marine plants, &c. on the shores of Ireland from north to 

 south," W. Thompson. A common species on the Ayrshire coast and 

 partial to the Laminarise, Rev. D. Landsborough. On the same 



