366 



FORMS OF LEPRA LI A. 



beautifully exhibited, some shut up closely in their homes, sonic 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. 



An allied species is called Lepralia landsooromi. In the Lepralia, as well as the Mem- 

 branipora, 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, Plustra, 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, becomo 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 poly- 

 zoa ry spreads from a centre ; 

 and that, although a free gem- 

 mule 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 con- 

 siderable size, it is not unfre- 

 quent 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. 



The Lepralia spinifera 

 differs through 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. The 

 Lepralia trispinosa is distinguished by three long spines from which it derives its name. 



A large and interesting genus with about forty or fifty known species, comprises the 

 species of Lepralia, Eschara, Lunulites, Cupularia, and Selenaria. Among these especial atten- 

 tion must be drawn to Lepralia monoceros, or the Unicorn Lepralia, so called on account 

 of the single horn, or club, with which it is furnished ; the Lepralia alata, or Winged Lepralia, 

 remarkable for the classically elegant sculpturing and the projecting "wings;" and the 

 Lepralia variolosa, so called on account of the peculiar mottlings which are thought to bear 

 a resemblance to the face of a person seamed with small-pox. 



The spoor-like avicularium of the Oellepora fusca is a creature 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, ; • ; It is a native of Bass's Straits. Two tolerably common species 

 are the Eschara fnliaeea, so called from its superficial resemblance to the scar left by a 



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NET-PORED ANIMAL.— Retepora ctllulusa. 



