the Crinoidea, Cystidea, and Blastoidea. 155 



Further on Dr. Carpenter says :— 



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

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

 gether dissimilar to ordinary prehension ; for, recognizing the fact 

 that the alimentary particles must be of small size, he supposed 

 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 the mechanical action of the digitate 

 papillne which fringe their borders. This doctrine he appears to 

 have abandoned, since, in his last account of this type (Hist. Nat. 

 des Echinodermes, p. 194), he affirms that the transmission of alimen- 

 tary particles along the ambulacral (?) furrows is the result of the 

 action of cilia with which their surface is clothed. 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 am therefore disposed to believe 

 in their existence. Such a powerful indraur/ht, moreover, must he 

 produced about the rer/ion of the mouth, hij the action of the large cilia 

 which (as I shall hereafter describe) fringe various parts of the in- 

 ternal wall of the alimentary canal, as ivould materialhi aid in the 

 transmission of minute particles along those portions of the amJmla- 

 C7'al('?) furrows ivhich immediately lead towards it; and it is, I feel 

 satisfied, by the conjoint agency of these two moving powers that 

 the alimentation of Antedon is ordinarily effected. In the very nu- 

 merous specimens from Arran the contents of whose digestive cavity 

 I have examined, I have never found any other th^n microscopic 

 organisms ; and the abundance of the hoi-n y rays of Peridinium tripos 

 (Ehr.) has made it evident that in this locahty that Infusorium was 

 one of the jirincipal articles of its food. But in Antedons from other 

 localities I have found a more miscellaneous assemblage of alimen- 

 tary particles, the most common recognizable forms being the horny 

 casings of Entomostbaca or of the larva) of higher Ckustacea." 

 {Op. cit. p. 700.) 



The existence of large cilia within the intestinal canal, ca- 

 pable of producing a powerful indraught of water, renders any 

 movement or concurrent action of the arms quite unnecessary 

 in the ingestion of food. It does not matter, therefore, in what 

 part of the body the mouth of a Crinoid may be situated, or 

 how remote from the reach of the arms. Attached perma- 

 nently to the bottom of the sea by their columns, tlie palasozoic 

 Crinoidea, Cystidea, and Blastoidea remained, wdiile feeding, 

 most probably motionless, drawing in streams of water through 

 their mouths by the action of their intestinal cilia. The long 

 tubular proboscis Avith which many of the species are provided 

 would thus be analogous in function to the siphon of the 

 Acephalous Mollusca. The indigestible particles Avould be, 



11* 



