14 PLATYCRINID.?!. PLATYCRINITES. 



by which some knowledge of the manner in which many species of Criiioidea sought for 

 and procured their food, might be arrived at. Bearing this in mind, and considering 

 the peculiar construction of the column in the Platj/criiiites, where the elliptical joints 

 possessed a tendency to assume an oblique direction ^vith respect to each other, and 

 wliich was imdoubtedly a very common position, for many colunans are found with the 

 joints placed at various angles to each other, we have sufficient evidence to prove that 

 the animal, duiing life, possessed the power of twisting its column to a very considerable 

 extent. 



Reflecting on the uses for which this exceedingly flexible column was designed, and 

 the purposes to which it might be applied in the animal economy, we are led to beheve 

 that the peculiar form of the column of Platycrinites %vill furnish a satisfactory explana- 

 tion of their manner of alimentation, and of the Crinoidea generally, when taken in 

 conjunction -with other striking points of structure. 



It is supposed that when the animal was impelled by the natural desire to seek a 

 supply of nom-ishment, and its net-like rays were spread in vain, that it then bent its 

 column iiato the form of an arch, vmtil its body was brought in contact ^vith the objects 

 on a level with its base, and the animal was thus enabled to secure any particle of 

 nourishment within reach of its proboscis or tentacvda. 



In some such manner as this it is imagined the Platycrinites obtained a great portion 

 of their food. Those ■with elongated oral tubes, if we are right in our conjectiu'es, were 

 enabled to search for and captm-e minute objects, such as the ova of mollusca, in the 

 deep crannies and fissiu-es at the bottom, which were no doubt then, as now, the recep- 

 tacles of nimierous colonies of embryo marine animals, and which must have fimiished 

 an abundant supjily of food to the beautiiiil radiated creatures, whose numbers were so 

 great, that during the greater portion of the period when the carboniferous strata were 

 in the course of accuraiilation, the ocean bed was covered with them as with a forest ; 

 and though irruptions of matter inimical to crinoidal life were fi-equent dm-ing that 

 period, and consigned thousands of them to a sudden destruction, yet did new genera- 

 tions speedily reappear to people the submerged sui-face, in place of those destroyed, 

 that it is evident they were meant to perform an important part in the great and all 

 WISE system of creation. 



It is not improbable that some species of crinoids were enabled to capture, and feed 

 on the small testaceous animals which came within range of then- closing rays. In such 

 cases the rays were admirably fitted to detain the captive moUusk, while the proboscis 

 was extracting its substance or juices. Or minute molluscous animals may have been 

 sucked in and gorged by the oral appai-atus. 



The Platycrinites appear to have associated together in considerable numbers, for we 

 ha^'e found them in groups composed of twenty or tliu-ty individuals ; and though traces 

 of other genera may occasionally be found associated Avith them, yet such accidental 



