194 THE CANADIAN NATURALIST. [June 



animals (as Annelids, or Entomostracans and other small Crusta- 

 ceans) with arms, and have never yet seen the smallest attempt 

 on the part of the animal to seize them as prey. Moreover, the 

 tubular tentacula with which the arms are so abundantly furnish- 

 ed, have not in the slightest degree that adhesive power which is 

 possesed by the " feet" of the Echinidea and Asteriada ; so 

 that they are quite incapable of assisting in the act of prehension, 

 which must be accomplished, if at all, either by the coiling-up of a 

 single arm, or by the folding- together of the arms. Now I have 

 never seen such coiling up of an arm as could bring an object 

 that might be included in it into the near neighbourhood of the 

 mouth ; nor have I seen the contact of small animals with a 

 single arm produce any movement of other arms towards the 

 spot, such as takes place in the prehensile apparatus of other 

 animals. Moreover, any object that could be grasped either by 

 the coiling of one arm, or by the consentaneous closure of all 

 the arms together upon it, must be far too large to be received 

 into the mouth, which is of small size and not distensible like 

 that of the Asteroid A." ^ 



Farther on Dr. Carpenter says : 



" It was affirmed by M. Dujardin (I'lnstitut, No. 119, p, 268) 

 that the arms are used for the acquisition of food in a manner 

 altogether dissimilar to ordinary prehension ; for recognizing the 

 fact that the alimentary particles must be of small size, he suppos- 

 ed that any such, falling on the ambulacral (?) furrows of the 

 arms or pinnae, are transmitted downwards along those furrows to 

 the mouth wherein they all terminate, by mechanical action of 

 the digitate papillae which fringe their borders. This doctrine he 

 appears to have abandoned ; since in his last account of this type 

 (Hist. Nat. des Echinoderms, p. 194) he affirms that the trans- 

 mission of alimentary particles along the ambulacral (?) furrows 

 is the result of the action of cilia with which their surface is clo- 

 thed. Although I have not myself succeeded in distinguishing cilia 

 on the surface which forms the floor of these furrows, yet I have 

 distinctly seen such a rapid passage of minute particles along 

 their groove as I could not account for in any other mode, and 



* Eeaserches on the Structure, Physiology, and development of Ante- 

 don {Comatula, Lamk.) rosaceus.—Voii I. By ~W. B. Carpenter, M.D., 

 F.R.S. Philosophical Transactions of the Eojal Society, vol. clvi, 

 Part II. 186G. 



