28 REMARKS ON THE PRINCIPLES OF 



out how exactly it is suited to the place I assign to it, completing the 

 five classes of Articulata. 



Passing to the sub-kingdom Mollusca, we find Dr. Dawson giving 

 as the four classes, Cephalopoda (about which and its position there 

 can be no difference of opinion) ; Gasteropoda, in which he includes 

 Pteropoda ; Lamellibranchiata ; and Molluscoida. I must begin by 

 remarking that the latter name is entirely inadmissible, having been 

 intended by its author to designate a distinct sub-kingdom, so far 

 resembling or approaching Mollusca as to be well named from that 

 circumstance, but not regarded as included in them. When the 

 group so designated is received as a class of Mollusca, a more 

 suitable name must be found. In this I have no doubt that Dr. 

 Dawson agrees with me, though in drawing up this paper he did not 

 judge it necessary to introduce a new term, indicating the animala 

 intended bj'^ one already applied to them. I would also propose it as 

 a query whether the Palliobranchiata or Brachiopoda are not better 

 considered according to Vander Hoeven's method, as a sub-class of 

 the same group with Lamellibranchiata, to which as a whole the name 

 Conchifera may be appropriated. It is more important to observe 

 that Gasteropoda have no pretensions, even among the sluggish 

 Mollusca, to be regarded as a motive class. Their place is as repre- 

 sentatives of the higher nutritive development, whilst Conchifera, 

 both in their mode of appropriating their food and in their general 

 figure, express the lower nutritive or fourth class, and allowing 

 Tunicata, of which Polyzoa (I must ask pardon for another verbal 

 criticism, but surely the law of priority gives our distinguished coun- 

 tryman Thompson's name a right to be preferred to Ehrenberg's 

 name, Bryozoa), are only a sub-class, to be rightly placed, we have 

 but to restore the active Pteropoda to their natural and generally 

 admitted position as a class, which a critical examination of their 

 structure would most fully justify, to find the five tendencies fully 

 represented in this sub-kingdom ; and I submit that in this and the 

 previous case respecting Articulata, it is not I who am chargeable 

 with creating a class on slight grounds to support a theory, but my 

 friend who sees the arguments for suppressing these classes magnified 

 to his view by the requirements of his theory. 



I have sufficiently expressed already my objections to Protozoa 

 being numbered with Radiata, to which they have, so far as I can see, 

 no real structural resemblance, and receiving them as a sub-kingdom ». 



