J, Rofe — Notes on the Crinoidea, 245 



to be the mouth, describes it as being situated in the centre of a 

 plated integument which extends over the abdominal cavity, and is 

 capable of being contracted into a conical or proboscidial shape ; 

 and Messrs. Austin also express their opinion that some Crinoids 

 had a limited power of expansion and contraction of the upper part 

 of the body. This change of shape would be permitted by the 

 membrane under consideration, supposing it to be elastic, and it is 

 very probable that the whole test, like the Echinidan alluded to by 

 Dr. Carpenter, was to a certain extent pliable and capable of adapt- 

 ing itself to thjQ necessities of the animal ; for we rarely find two 

 specimens of even the same species exactly symmetrical ; the dome 

 in many cases, where proboscidial, being elevated so as to form a 

 cone, at the summit of which is the proboscis, whilst in other speci- 

 mens of the same species, identical in every plate and found in 

 close proximity, the dome is nearly flat and the proboscis projecting 

 but little from it. The axis of the calyx also is frequently not in 

 a right line with that of the column^ the base plates of the cup 

 being apparently slightly contorted, giving it the appearance of 

 drooping or leaning to one side. The plates of the calyx are also 

 frequently distorted (although not fractured), as if by pressure, 

 thus showing an amount of flexibility or elasticity. The com- 

 pressibility of the investing membrane, if not of the plate itself, 

 is also evidenced by the not uncommon occurrence of a portion of 

 a column, when falling to pieces by the decay of its membrane, 

 being pressed against and becoming partially imbedded in a plate of 

 a calyx, and, when removed, leaving such a mould as would be the 

 result of its being squeezed into a plastic material. 



Before considering the application of this power of expansion and 

 contraction, we may shortly refer to another point in the organiza- 

 tion of the Crinoids. In the year 1858 Mr. Billings, in '' the 

 third decade of the Canadian Organic Eemains," announced the 

 existence in some of the Crinoids of certain " tunnel-like passages, 

 which lie under the external plates and extend nearly to the apex of 

 the dome," and in 1865 these passages were more mmutely de- 

 scribed by me in a paper in this Magazine, Vol. II., p. 245, and it 

 was there suggested that they might be for the purpose of supply- 

 ing food to an internal mouth as well as water for respiration. 

 Since that date Professor Loven has published an account of a recent 

 Austi'alian Echinoderin (Crinoid?), the Hyponome Sarsi, Loven, from 

 which the following description is extracted : — 



"The general appearance of this very remarkable Echinoderm is 

 that of a small Star-fish, or a Euryalid. It has a disk, convex on 

 the ventral surface, flattened on the dorsal." " As in the recent 

 genera, Antedon and Pentacrinus, a large conical proboscis-like funnel 

 rises in one of the interradial spaces of the ventral surface of the 

 disk, and from a point situated a little before the centre of the same 

 surface five narrow channels, protected by marginal scales, radiate 

 and defurcate thrice, and run out on the rays and their branches." 

 '•' On the rays the channels are open, but upon the disk between 

 their fixst bifurcation and their common starting-point, their marginal 



