ON A NEW SPECIES OF AGELACRINITES. 363 
‘assume, that, in the Radiata, there are certain natural groups (not 
yet thoroughly worked out) which are perfectly unconnected with 
each other; and in which, respectively, the higher forms foreshadow 
an advanced type of structure, whilst the lower forms present the 
normal type. ‘The higher forms of a low group, however lowly 
organized as to their entire structure, will be thus in certain respects, 
in advance of the lower forms of a higher group. Whatever grounds 
there may be to believe that some law of this kind really holds good 
in Nature, its application in the present place would be evidently 
forced. Discarding therefore the idea, that, in the pyramidal orifice 
of the Cystideans and Agelacrinites, the mouth is represented, this 
latter organ must be sought for in another place. Reasons have 
already been stated against this being the centre of the rays. Its 
true position will be found, I believe, in the centre of the under side 
of the body. But—it may be urged in objection to this—the genus 
Agelacrinites is sessile : is attached by its under surface to shells and 
other foreign bodies: and hence the mouth cannot be there situated. 
Several examples, it is quite true, have been met with attached in 
this manner to brachiopod shells ; but this is by no means a general 
condition of occurrence; and, rightly considered, is no proof of an 
original permanent attachment. It is just as exceptional a mode of 
oceurrence, indeed, as that from which Vanuxem derived the name 
of the genus. 
This suggestion as to the true position of the mouth, cannot, of 
course, be satisfactorily adopted, until confirmed by the examination of 
more perfect specimens than those hitherto discovered; or until the 
proper functions of the pyramidal orifice, in this genus and in the 
cystideans, are clearly ascertained. But under any view, it seems 
obvious, that, without a forced collocation, these peculiar forms cannot 
be placed in any existing group. In the present restricted state of 
our knowledge, at least, they must form a group apart. Mr. Billings 
(Decade III. of Canadian Organic Remains, under description of 
Agelacrinites Dicksont) appears inclined to regard them as constituting 
a sub-order of Star-fishes ; and he proposes to arrange them in this 
connection, under the term of Hdrio-asteride. This name seems 
objectionable, however, on two grounds: first, because the supposed 
sessile (id est, parasitic,) condition of Agelacrinites is by no means 
proved; and secondly, because the relations of the genus to the 
Star-fishes—in so close a way, at least, as the name would imply—is 
