262 John Rofe — Notes on the Crinoidea. 



IV. — Further Notes on Crinoidea. 



By John Rofe, F.G.S. 



(PLATE XI.) 



DUEING several years I have had frequent opportunities, in my 

 spare time, of collecting and studying the Crinoidea, par- 

 ticularly those of the Carhoniferous formation ; but I have not had time, 

 nor do I feel competent, to treat this subject fully in all its bearings. 

 Perhaps, however, a few further notes on what I have observed in 

 connexion with them, and in their relations with the recent as well 

 as with those found in the several geological formations, may have 

 an interest for some of your readers, or may be suggestive of further 

 examination by some one better qualified, by physiological know- 

 ledge, for the inquiry. 



Crinoidal Limestone, independent of the palasontological interest 

 it possesses, has considerable geological importance, as from it may 

 be deduced evidence of alternations in the depth of the sea in which 

 the Crinoids flourished, sometimes, from their condition, suggesting 

 great depth and clear water, and sometimes shallow water adjacent 

 to a shore, or at an intermediate depth ; and the great abundance of 

 these remains, found under these different circumstances, make them 

 worthy of more consideration in detail than they have yet received. 

 Crinoids occur in most of the geological formations, particularly in 

 the Palaeozoic series ; but they are found in the greatest profusion, 

 both in number and in variety of species, in the Mountain Limestone : 

 and I will therefore take this formation as the type, as most of the 

 remarks I may make on it will apply to other strata in which 

 Crinoids in any number occur. 



In many places, particularly in the Pennine Chain in Westmore- 

 land, Lancashire, Yorkshire, and Derbyshire, beds of this formation 

 are composed almost entirely of portions of the columns or stems of 

 Crinoids of different genera and species, varying from one to eighteen 

 lines in diameter, but generally in short lengths. 



In this mutilated condition these stems frequently occur in beds 

 some feet in thickness, and so cemented together that they form a 

 hard rock or marble, which takes a good polish, and is extensively 

 used in this district for mantelpieces, tables, and other decorative 

 purposes. One circumstance, however, is very remarkable, that 

 amongst the innumerable portions of the columns, a calyx or head 

 of any species is veiy rarely indeed found in the hard Limestone or 

 marble rock itself, and what are found are generally in relief im- 

 bedded only partially in the upper surface of the rock and covered 

 with shale or other parting between the Limestone beds. Those 

 found with the arms, or with more than a few plates of the 

 column, are, I believe, invariably in this condition. Sometimes the 

 Crinoidal exuviae are more or less mixed with shells and corals, and 

 are less consolidated, and can be used only as a building-stone or 

 for lime-burning; and in other cases the fossils are disj)ersed in beds 

 of calcareous or agillaceous shale between the beds of Limestone. 

 The heads, however, are occasionally found in considerable numbers, 



