4-50 FORMS OF LEPEALIA. 



been cemented upon it. This substance is indeed closely allied to the Sea Mat, and is 

 chiefly to be distinguished by the membranous nature of the polyzoary, which will not 

 permit it to stand boldly erect after the manner of the true Sea Mat. At fig. H is 

 shown a small mass of the Membranipora pilosa, as this species is called, surrounding 

 the stem of a seaweed, and at I, a small portion of the same creature is given in order to 

 show its aspect when magnified. 



As may be seen from the illustration, the feathery plume of tentacles is extremely 

 graceful, and, when the creature is living, has a remarkably elegant effect. In a specimen 

 now before me, viewed by a power of only thirty diameters attached to the binocular 

 microscope, the polypes of the Membranipora are beautifully exhibited, some shut up 

 closely in their homes, some just putting forth their heads from the cells, others half 

 protruded, and a few with the plumy tufts displayed in all their beauty. It is as well to 

 view this and other polyzoa with different kinds of illumination, both as opaque and 

 transparent bodies ; artificial light is, however, to be avoided. 



Fig. K represents a magnified portion of an allied species, Lepralia Landsborovii. In 

 the Lepralia, as well as the Membranipora, the process of development is very interesting, 

 especially as it can be readily watched under the microscope. 



Towards the end of May, specimens of Lepralia, Flustra, and Membranipora should 

 be procured and placed in shallow glass vessels containing sea-water. After a little time, 

 minute beings, much resembling the ordinary infusoria, are seen swimming about. 

 Presently, the " gemmules," as these creatures are technically named, become stationary, 

 affix themselves to some definite spot, and develop a feather-covered polype, being now 

 similar in shape to a single cell of the species from which it was produced. Buds, or 

 projections, are soon formed at the sides, which are rapidly developed into new cells, and 

 in their turn are the means of putting forth new cells. Thus it will be seen that each 

 polyzoary spreads from a centre ; and that, although a free gemmule is capable of 

 producing stationary cells, the greater number of cells have never passed through the 

 state of their original progenitor. When a polyzoary has attained a considerable size, 

 it is not unfrequent to find the margins of the group filled with vigorous and lively 

 polypes, being those last produced, while the centre is composed of empty cells, the original 

 inhabitants having died out from old age. 



. At figs. L and M we observe two portions of Lepralia spinifera, given for the purpose 

 of showing the short sharp thorns with which the edges of the cell are guarded, and the 

 curious ovicell, notable for its beautiful sculpturing of ridges radiating around a centre. 

 Fig. N is the Lepralia trispinosa, distinguished by the three long spines from which it 

 derives its name. 



On Plate IV. in figs. A to J inclusive, are represented some of the forms assumed by 

 this large and interesting genus, which comprises between forty and fifty known species. 

 Among these especial attention must be drawn to Lepralia monoceros, or the Unicorn 

 Lepralia (fig. C), so called on account of the single horn, or club, with which it is furnished ; 

 the Lepralia alata, or Winged Lepralia (fig. B), remarkable for the classically elegant 

 sculpturing and the projecting "wings ;" and the Lepralia variolosa (fig. G), so called on 

 account ol the peculiar mottlings which are thought to bear a resemblance to the face of 

 a person seamed with the small pox. 



At fig. K is shown the spoor-like avicularium of the Cellepora fasca, a polyzoon notable 

 for its urn-shaped and chalky, stiff cells, arranged either irregularly or in the form 

 of a quincunx, i. e. like the cinque spots on a die, ; I It is a native of Bass's Straits. A 

 tolerably common British species, Eschara foliacea, so called from its superficial resem- 

 blance to the scar left by a deep wound, is given at fig. L, and a very curious polyzoon of 

 the same genus, Eschara flalellaris, may be seen at fig. M, and is remarkable for the hood 

 or helmet-like ovicells. About eleven species of this genus are known. 



At fig. 1ST is shown one of the most curious of the polyzoa, named, from the external 

 resemblance which its apertures present to the meshes of a net, the Retepora, or Net-pored 

 animal. The polyzoary of this species is hard, chalky, is only pierced on one surface, and 

 has so much the appearance of the true stony corals, that it might easily be mistaken for 



