304 POLYZOA INFUNDIBULATA. 



The cells of L. tenuis are many of them nearly parallel, with their 

 apertures on the same line, but the greater number follow the typical 

 semialternating fashion. They are more widely apart than usual, 

 and the interstitial basis is singularly punctured. These punctures 

 are comparatively large, arranged in one series or, in some parts, in 

 two ; and they become more numerous and irregular in the space 

 between the termination and origin of the cells. There is frequently 

 a knob or loop in this part. The sides of the walls of the cell are 

 apt to be split into short spines, for this is one of several species that 

 can assume the similitude of Flustra lineata. 



In certain circumstances, and from age, the walls of the cells be- 

 come calcareous, thickened and opaque ; and then also we perceive 

 that there is a knob above and behind the upper lip of the aperture. 

 Cells, however, in their perfect state, with their thin, clear parietes, 

 may generally be detected at the circumference of the crust ; and I 

 have not seen a specimen in which the catenated pores were ob- 

 literated. 



3. L. ASSIMILIS. " crust transparent ; cells rounded supe- 

 riorly ; apertures triangular and mostly furnished with an 

 acuminate operculum. A large and very blunt process is 

 placed beneath each aperture.' 1 ' 1 A. H. Hassall. 



Hob. " Four specimens are on old valves of Pecten maximus : 

 Dublin Bay," A. H. Hassall. 



" It is no easy matter at first to distinguish this species from the 

 preceding (L. tenuis), from which, however, as well as from L. hya- 

 lina, I am satisfied that it is distinct." A. H. Hassall. I have seen 

 no specimen of L. assimilis, and in Mr. Hassall's description I can- 

 not find a character by which it can be distinguished from L. tenuis. 



4. L. HASSALLII ; cells cylindrical, smooth and opaque, the 

 aperture wide, circular, with a thick rim and a large knob open 

 on each side. A. H. Hassall. 



PLATE LIV. FIG. 3. 

 Cellepora bimucronata, Hassall in Ann. and Mag. Nat. Hist. vii. 367. pi. ix. fig. 1. 



Hob. On shells, rare. On Patella coarulea, coast of Aryshire, 

 Rev. D. Landsborough. Dublin Bay? A. H. Hassall. 



Crust spreading irregularly, rather thick, but closely adherent, 



