226 THE MICROSCOPE. 



Lepralia, Sea-scurf, from the Greek for marine leprosy, is the 

 name given to this branch of the Celleporidae by Dr. Johnston. 



Lepralia nitida, found attached to shells, is thus described: "Crust 

 spreading circularly, closely adherent, rather thin, greyish white, cal- 

 careous ; cells contiguous, in radiating rows, large, subalternate, orate, 

 ventricose, silvery, the walls fissured with six or seven cross slits which 

 are on the mesial line ; aperture subquadrangular, depressed, terminal ; 

 anterior to it there is often found a globular, pearly, smooth, oviferous 

 operculum, with a round even aperture. The remarkable structure of 

 the cells renders this one of the most interesting species under the 

 microscope. There is sometimes an appearance of a spine on each side 

 of the lower angle of the mouth, which is merely the commencement 

 of the walls of the next cell." 



L. coccinea, L. variolosa, L. ciliata, L. trispinosa, and L, immersa, 

 are the other British species. 



The family Cellularia, or little cells, have mostly that wonderful 

 provision of nature for their protection, an operculum, a lid or cover 

 over the apertures of their cells. Cellularia ciliata is parasitical, 

 branching, calcareous, white and tufted ; grows about half an inch in 

 height, and the oblique aperture is armed on the outer edge with 

 four or five long hollow spines. The operculum is pearly, and near 

 the base there is that singular appendage, described as the bird's- 

 head process. Its beauty and transparency render it a favourite object 

 with microscopists. 



Cellidaricu avicvlaria has been more accurately described by Mr. 

 Gosse, from his own observations upon specimens secured on the Devon- 

 shire coast, during a residence there. He says : " Well does it deserve 

 the name of Bird's-head Coralline, given to it by the illustrious Ellis ; for 

 it presents those curious appendages that resemble vultures' heads in great 

 perfection. All my specimens were most thickly studded with them ; 

 not a cell without its bird's head, and all see-sawing, and snapping, 

 and opening their jaws with the most amusing activity; and what was 

 marvellous, equally so in one specimen from whose cells all the polyps 

 had died away, as in those in which they were still protruding their 

 lovely bells of tentacles. The stem ascends perpendicularly from a 

 slender base, which is attached to the rock, or to the cells of a Lepralia 

 growing from the rock. The central part of the spine is most ex- 

 panded, the diminution above and below being pretty regular; during 

 life, the usual colour is a pale buff, but the cells become nearly white in 

 death. When examined microscopically, it is, however, that the 

 curious organisation of this zoophyte is discovered, especially when in 



