CRINOID GENUS SCYPHOCRINUS 9 



At the famous colony of Crawfordsville, where the soft layers are much 

 thicker and without any distinct capping of hard limestone, the crinoids were 

 more gradually deposited, and are found more generally diffused throughout 

 the beds. But in other cases as usually found the colonies were quickly 

 killed by a change in the content or condition of the water, and settled quietly 

 into the soft mud in a thick mass, followed by a calcareous or siliceous deposit 

 producing limestone or chert above them ; thus the parts next to the mud were 

 largely preserved intact, while those above them were crushed, flattened, or 

 consolidated by the pressure and more or less cemented into rock, which would 

 thus form a firm backing for the specimens below it. If there were a strong 

 current, the stems and crowns of the crinoids would be swept away, while any 

 imbedded or firmly anchored roots would remain in the mud; and they might 

 or might not become attached to a firm layer above them according to the 

 character of the deposit immediately following. A limestone plate would not 

 be so likely to form, owing to the removal of the other calcareous parts of the 

 crinoids which would help to produce it. 



The occurrence at Keyser, West Virginia, mentioned in Mr. Schuchert's 

 paper (p. 260) where he saw ten Camarocrini upon a large slab detached from 

 nearly vertical strata by blasting, must be considered in the light of these facts. 

 I have not the least doubt that they were upon the under side of the layer as 

 originally situated, and that the unstalked end as presented by nearly all the 

 bulbs which he saw partly buried in the mud was the under part as they had 

 rested in the sea bottom. The small slab from Oklahoma, with five specimens 

 on the "upper" surface (ibid., p. 261, pi. 43), was no doubt in the same 

 condition; so that the bulbs, "not one of which had the stalk end turned 

 upward," are actually seen from the under side, and not the upper. There is 

 no direct evidence of the original position of these slabs in the strata from 

 which they were derived, so that it cannot be positively asserted that the surface 

 carrying the specimens was the upper; whereas the overwhelming probability, 

 from analogy of similar occurrences elsewhere, is that that the reverse is true. 



CONCLUSION AS TO CAMAROCRINUS 



While, therefore, there can no longer be the slightest doubt that the 

 objects known as Camarocrinus were the bulbous distal ends of the stems of 

 Scyphocrinus, it is obvious that with the foregoing fact established as to the 

 position of these bulbs, the theory that they served as a float loses much of its 

 force. That supposition, always at best a somewhat forced one, is no longer 

 necessary, since the upright position of the bulbs is perfectly consistent with 

 the simpler and more natural idea that they served merely as enlarged roots, 

 by which the crinoids were permanently or temporarily fixed to the sea bottom. 

 The fact that these bulbs are often found in large beds without other accom- 



