﻿SCHUCHERT] siluric \\i> devonic cystidea 



263 



( 'amarocrinus 1 [all ( emend. ) 

 (Plates XL XI. IV) 

 Pyriform, spheroidal or depressed spheroidal chambered bodies, 

 composed of a great number of small plates to one end of whirl) arc 

 attached roots and a short stalk of the -aire nature as those of 

 crinoids. There is no evidence of ambulacra, mouth, or anus. Imme- 

 diately inside the base of the bulb is a large, more or less pentagonal 

 medio-basal chamber, around which are usually arranged 5 or 6, and 

 more rarely as many as n variously shaped chambers. The walls 

 of the camane have their origin in hi furcations of the roots beneath 

 the stalk. The walls of the chambers are double and are made up 

 of small, irregularly shaped plates, the walls for the greater part 

 closely adjoining and parallel, and united to one another by many 

 short, stout, blunt processes. Along the periphery of the theca these 

 walls bend over quickly and unite with one another in such a manner 

 that from 5 to 11 interradial, large hollow lobes or water chambers 

 are formed. Each lobe has a large opening in the base of the theca 

 immediately inside the lateral basal extension or basal rim of the 

 outer wall. The inner walls are surrounded by an outer integument 

 of innumerable small plates devoid of regular arrangement. The 

 origin of this outer wall is independent of the roots. Communicat- 

 ing pores, irregularly distributed, exist between the plates of both the 

 outer and inner walls, except those of the base beneath the medio- 

 basal chamber. 



In very young specimens, nearly all of the outer integument has 

 irregularly distributed functional pores between the plates, but in 

 older examples a more or less thick, amorphous secondary coating 

 occurs over about one-third of that end of the bulb to which the stalk- 

 is attached, closing all the pores of this region. Very often in old 

 specimens of C. ulrichi, encrusting animals are found upon this 

 secondary coating, as Edriocrinus, bryozoa. and brachiopoda {Lcp- 

 tccnisca). By this condition of preservation it is natural to infer that 

 the pores between the outer plates were functional ( for the oxygena- 

 tion of the blood?) and that no parasitic animals attached themselves 

 to any part of the bulb until the secondary coating was deposited. 



In many of the Indian Territory specimens the lower part of the 

 bulb is prolonged into a high, thick-walled collar 10 to 15 mm. high, 

 and in such there is always about the same length of stalk preserved. 



The shape and size of the medio-basal chamber are very variable. 

 In some it is large and regularly pentagonal in transverse section. 

 gradually tapering upward between the walls of the surrounding 



