CRINOID GENUS SCYPHOCRINUS II 



and wavy edge, is one. Lichenocrinus Hall/ which Schuchert ' says " represents 

 the nearest approach of a modified crinoid root to Camarocrinus," is another. 

 This curious disk-like body, composed of numerous rounded plates, has been 

 the subject of much discussion, but is now known to be the encrusting root of 

 a very small crinoid of the Heterocrinus type. Specimens with long stems 

 attached were figured by Meek, but not until recently has evidence of the 

 associated crown been obtained. This important discovery was made by 

 Dr. George M. Austin, of Wilmington, Ohio, who has generously placed his 

 material in my hands for description. 



An analogous type of growth is seen in Edriocrinus,' which has no stem, 

 but either is attached to other objects directly by the encrusting base (like the 

 Recent genus Holopus), or becomes free with the base rounded or extended 

 downward by secondary growth into a large, conical mass which might have 

 rested on the sea bottom or might have been moved about by currents. 



That Camarocrinus is rounded and somewhat smooth below is not an 

 objection to the view that it served the function of fixation of the crinoid in 

 the mud. A perfectly analogous case may be seen in the living Alcyonarian 

 polyps, the Pennatulids, which have a very similar kind of bulbous root by 

 which they are habitually fixed to the bottom. In fact, a species of Pennatulid, 

 Umbellularia encrinus (Pennatula encrinus of Pallas), was treated by Ellis ' in 

 1753, and by authors generally down to Lamarck as analogous to the stalked 

 crinoids. To show the resemblance of its permanently fixed root to the bulbous 

 Camarocrinus, I give herewith a photograph of a specimen of the Pennat- 

 ulid, Ptilosarcus brevicaulis Nutting, from Cape Tsiuka, Japan, 44 fathoms 

 (No. 30057 of the National Museum collections. PI. VII, fig. 5). The exterior 

 of this bulbous root is smooth, as is that of Camarocrinus. Some forms of 

 Pennatulids have a long slender stalk with a root much more elongate than this, 

 but still of an essentially bulbous type. It is further significant that among the 

 Coelenterates are found the same three modes of attachment as in the crinoids, 

 namely, by branching roots, flat disks, and bulbs. 



Many such enlarged roots of marine organisms tend to develop some kind 

 of septa or partitions for greater rigidity, dividing them into chambers of more 

 or less irregular form and size. This is the case in Camarocrinus, where the 

 chambers are formed of walls which in large part seem to be double in the cross- 

 sections, as will be explained farther on. When the specimens occur in beds 

 by themselves, without other accompanying remains of the crinoids, they are 

 usually rotund, solid, and heavy; whereas when mingled with the stems and 



'24th Rep. N. Y. St. Mus. Nat. Hist., p. 216, pi. 7, figs. 1-7, 1872; Meek, Geol. Surv. Ohio, Pal., 

 vol. 1, pp. 44-51, pi. 3, figs. 1, 2, 1873. 

 a Op. cit., p. 268. 



"Nat. Hist. New York, pt. 6, Pal., vol. 3, p. 143, pi. 87, figs. 1-22, 1859. 

 ' Philosophical Transactions, vol. 48, p. 305. 



