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ALDER, ON NEW BRITISH POLYZOA. 95 
H. Scuréver (Hamburg, 37) exhibits some very common- 
place microscopes. 
A few unimportant instruments in this class may possibly have 
been overlooked in the foreign department. 
Descrirtions of new British Poryzoa, with Remarks on 
some imperfectly known Seucius. By Josuua Auper, Esq. 
Tue branched calcareous Polyzoa have always commanded 
attention, from the beauty of their form and structure, while 
at the same time naturalists have experienced considerable 
difficulty in defining their specific distinctions. My object 
in the present paper is to endeavour to clear up some of the 
difficulties that beset the study of the British species, more 
especially in the genera Cellepora and Eschara, with regard 
to some species of which a more than usual difference of 
opinion exists. Dr. Johnston did much to unravel the syno- 
nyms of this class in his ‘ History of British Zoophytes.’ 
But it is to Professor Busk that we are most indebted for a 
knowledge of their peculiar structure, and a careful definition 
of their generic and specific forms. In his ‘ Catalogue of the 
Polyzoa in the British Museum,’ he points out the import- 
ance of those curious organs, the avicularia and vibracula, in 
the discrimination of species—an attention to which has very 
materially contributed to the accuracy of definition. The 
papers of the same distinguished observer, in the ‘ Journal of 
Microscopical Science,’ still further increased our knowledge 
of the British species, particularly in the description of those 
got in Shetland by our lamented friend, Mr. Barlee. Still, 
however, much remains to be done. The eminent Norwe- 
gian naturalist, Professor Sars, has lately published a valua- 
ble paper ‘On some Norwegian Polyzoa,’ which throws much 
light on our British species, and especially those of Shetland. 
With the assistance of specimens of his new genera, which 
Professor Sars has kindly sent me, I shall be able to clear up 
some points in our Polyzoa hitherto misunderstood, while at 
the same time I shall have the opportunity of mtroducing a 
few new species into the British Fauna. 
Genus CELLEPORA. 
Some of the species of this genus have lately been removed 
to Hschara, including Cellepora Skenei and C, levis; also 
