155 
Classification of the British Polyzoa . 
Fam. 4. Bicellariidae. 
Genera: Bicellaria, Blainville. 
Bugula, Oken. 
Species new to Britain, B. gracilis , Busk, var. uncinata. 
Beania, Johnston. 
Fam. 5. Notamiidae. 
Genus Notamia, Fleming. 
Fam. 6. Cellariidse. 
Genus Cellaria, Lamx. (part.). 
Fam. 7. Flustridae. 
Genus Flustra, Linnaeus. 
Fam. 8. Membraniporidae. 
In dealing with the section of the Polyzoa that includes the 
MemhranIgor idee and Escharidce of Busk, and some allied 
genera, there can, I think, be no doubt that, if we are seeking 
a natural classification, we must base the families, for the most 
part, on the characters of the zocecium. To found them on 
the manner of growth (however convenient the method may 
be as an artificial contrivance) would be to place the mere acci¬ 
dent before the essential elements of structure. Groups thus 
formed, instead of fitting in with natural affinities, would tra¬ 
verse them at all points. The venerable family of the Escha¬ 
ridce (auctt.) is a mere jumble of incongruous elements, and 
no more represents the order of nature (the actual relation¬ 
ships of the forms which compose it) than would a group of 
plants founded on the colour of their flowers. Whatever 
judgment may ultimately prevail respecting the constitution of 
genera , it will hardly, I think, be disputed that the first 
step towards a natural classification in this department must 
be the reform, in the sense which I have indicated, of the 
larger groups. 
Genera: Membranipora, Blainville. 
Megapora, Ilincks. 
Fam. 9. Microporidae. 
Genera: MlCROPORA, Gray. 
