1899] MICROSCOPICAL JOURNAL 233 



Lacuna radiata. — The flask-like cavity of this species 

 is rather deeply immersed in the containing fragment ; 

 the neck-like portion is considerably elongated and very 

 small in diameter. The exterior surface of the globular 

 portion is distinctly mammillated, and from each apex, 

 branched or unbranched, very fine hair-like processes are 

 produced, which reach the surface. 



They usually occur separately, but two may become 

 confluent; spore-like bodies having an amber tint are 

 present in some instances ; these escape through an erod- 

 ed aperture, which destroys the neck-like portion of the 

 organism. Widely distributed, but not very common. 

 British material has furnished the best examples— notably 

 Kenfig Pool, Bristol Channel. Found in shallow-water 

 deposits. Fig. 3 x 210. 



Lacuna radicans. — This species is very variable in form 

 and may consist of a sample of unbranched central cavity, 

 or they may assume various contours according to the 

 number of branches they produce. The central cavity, 

 however, is tolerably large, and gives off at frequent in- 

 tervals, around the margin, very fine and freely branched 

 filaments, usually decreasing in size towards their ex- 

 tremities. Always solitary. Not common Fig. 4 x 150. 



Lacuna moniliformis. — This organism consists of a 

 series of irregular-shaped Lacunae connected by filaments, 

 which, when fully developed, are freely branched and 

 liberally provided with short excretory ducts. This is 

 one of a few plants met with which appear to occupy an 

 intermediate position between the genera Lacunae and 

 Achlyae ; the characteristic features of both are intimate- 

 ly combined and balanced. Very rare. Challenger Station 

 No. 23, off Sombrero Island, West Indies, 450 fathoms. 

 Fig. 5 x 300. 



Achlya monile. — A small and very interesting organ- 

 ism; it is highly branched ; the filaments in their early 

 stage of growth have a distinctly septate appearance 



