116 



Series vi 



STUDY XXIV. FAMILIAE BRITISH BKYOZOA. 



THE Bryozoa better known in this country under the name of 

 Polyzoa often constitute a source of delight at meetings of our 

 Microscopical Societies ; seldom, indeed, is a microscopical conver- 

 sazione complete without at least one such exhibit set out proudly in 

 all the glory of parabolic or spot-lens illumination. The beauty of 

 the pellucid zooids in the full expansion of their glorious crowns of 

 elegantly tapered tentacles, sentient and responsive to the slightest 

 alarm, and the ceaseless lashing of the cilia clothing these tentacles 

 and creating vortices big with fate for many a tiny organism swimming 

 hard by, make up a picture wherein loveliness and interest chain the 

 attention alike of the greybeard in microscopy and of the tyro in the 

 science. 



As a rule, the fresh-water Bryozoa are the forms thus exhibited, 

 being the easier to procure in inland towns. The marine forms, how- 

 ever, are fully as beautiful, and in some respects are much more 

 interesting as diversity of form is infinitely greater. If anything, the 

 marine forms are even hardier than the fresh-water ones, and in these 

 days of rapid postal communication and of Marine Biological Stations, 

 inland microscopists have no difficulty in studying living marine 

 species, and of thus comparing them with those they obtain from 

 adjacent pond or sluggish canal. 



The Bryozoa are colonial in habit of life, except one minute form, 

 Loxosoma, found parasitic in multitudes of separate individuals upon 

 the hinder end of the great Spoon-worm (Phascolosoma). The colonies, 

 or zoaria, may be slender and branched (Botvcrbankia), broadly folia- 

 ceous (Flustra), massive and calcareous (Lepralia), coiled in elegant 

 spirals (Bugula), gelatinous as Lophopus and Alcyonidium, horny, hispid, 

 smooth, or crusting. Almost all live attached, usually to stones or 

 seaweeds, and often enough we find them growing in profusion upon 

 the carapace and limbs of crabs. One form, Cristatella, crawls freely, 

 with slug-like motion, over and amongst the weeds of its pond home, 

 while others, the Selenarida, swim by the oar-like paddling of giant 

 bristles the vibracula. Can diversity be greater? Well might the 

 earlier naturalists consider the slender forms to be zoophytes, and the 

 massive ones to be coral growth. 



Later, their affinities were recognised as apart from the zoophytes 

 by the possession of a well-developed alimentary canal. Now they are 



