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by Thompson in the singular number, and he speaks of it as 1 a new animal 
discovered as an inhabitant of certain zoophytes ; ’ and he afterwards says of 
the Flustrce that in many of them he had ‘ clearly ascertained the animals to 
be Polyzoce .’ Mr. Hincks maintains what is perfectly clear, that Thompson 
1 used the term Polyzoa (in opposition to Hydra) to denote a distinct type of 
structure which he had demonstrated ; ’ but we cannot follow him in holding 
that it c was not as the mere name of the single zooid,’ or that ‘ Polyzoa, as 
he (Thompson) uses it, is essentially a class-designation, and not the name of 
a mere structural element.’ We must place ourselves in Thompson’s 
position to understand precisely what he meant, and it seems to us that in 
the use of the term Polyzoa , in opposition to Hydra, he was merely 
following out the practice of some of the older systematists whose works he 
had studied, such as Linnaeus, who uses the term Hydra to designate what 
he calls the ‘flores’ of these very zoophytes, just as he used the terms 
Limax, Nereis, Tethys , &c., to indicate the general structure of the animals 
of his Vermes Testacea. In this sense and no other can we understand the 
peculiar mode in which Thompson speaks of his 1 Polyzoa.’ The term is 
used by him to express a ‘ structural element ’ of the composite organism, and 
not as a class designation. In fact, after reading Thompson’s memoir, it 
seems quite clear that he had not the slightest idea of founding a new and 
distinct class, or even order, of animals, as indeed may be seen from one of the 
passages quoted by Mr. Hincks in support of his own opinion, in which 
Thompson says, ‘ The Polyzoa will probably be found in many dissimilar 
genera of the zoophytes, and even mixed up with the Hydra in some, .... 
and hence this discovery must be the cause of extensive alterations and dis- 
memberments in the class with which they have hitherto been associated.’ 
Professor Rupert Jones puts the matter in another light, and holds that 
the class Bryozoa of Ehrenberg contains such incongruous elements (the 
Foraminifera forming one great division of it) that the adoption of this 
name is inadmissible, and that we must therefore discard it altogether and 
accept the name of Polyzoa for the class on the authority of Mr. Busk, who 
first made use of it as a definite class-designation. But it is to be observed, 
on the other hand, that the term Bryozoa was in use as the name of a class 
restricted nearly as at present many years before the adoption of the term 
Polyzoa by Mr. Busk, and this would again cause the scale to descend in 
favour of the former name. Moreover, Ehrenberg himself did not at first 
include the Foraminifera under Bryozoa. 
We have said so much about the Polyzoa and their name, that our 
reference to the book which has served as the text of this sermon can only 
be a brief one. This, however, is of the less consequence, as the only terms 
in which it can be spoken of are those of unmixed praise, and such laudations 
may be given in comparatively few words. The great body of Mr, Hincks’ 
work consists of the systematic description of the species of British Marine 
Polyzoa, of which he recognizes 235, many of them common on different 
parts of our coasts, others only obtained in certain places, or by dredging at 
considerable depths. The characters of these species, and of the genera, 
families, and higher groups to which they are referred, are most carefully 
described and discussed. Mr. Hincks has devoted particular attention to the 
varieties displayed by many species, which, as he justly indicates, have 
