378 PROCEEDINGS OF THE ACADEMY OF [1888. 



represents a true anal tube, whatever otlier function it may have 

 possessed. Nothing is known of the anal opening of EnaUocrinus. 



We give herewith new definitions of the Crotalocrinidae and their 

 two genera Crotalocrinus and EnaUocrinus, to take the place of 

 those given by us in the Revision, Part III, p. 143, and pp. 147 — 

 152, and we request all who may be using the Revision to substitute 

 them at once. 



We now direct attention to another point of considerable interest 

 which has been developed by this investigation. A very perplex- 

 ing figure was given by Angelin (PL XVII, fig. 2b), and a some- 

 what similar one by Murchison (Siluria, 8rd Ed., p. 247, fig. 5),. 

 Avhich show certain extensions apparently from the inner rim of the 

 first radials, and which superficially resemble the so-called "consoli- 

 dating apparatus" of Cupressocrinus. A closer examination of 

 Augelin's figure shows these extensions to be composed of small 

 plates ; both figures, however, are misleading, for our specimens 

 show that the plates forming those extensions do not rest against 

 the inner edges of the first radials as represented, but upon their 

 upper faces, as correctly shown in Angelin's PI. XVII, fig. 2a. 

 They are nothing but the exposed ventral surfaces of the second 

 primary and succeeding radials, the elevations being the projecting- 

 margins along the ambulacral grooves. Neither do they extend so- 

 far inward as would seem from Angelin's figure, they project in- 

 ward only for a short distance, and form underneath a surface of at- 

 tachment for certain organs hereafter described. 



Miiller described and figured correctly (0/;. cit. p. 189, PL VIII,. 

 fig. 5), the inward curvature of the plates, but we cannot agree with 

 him in his statement that bv means of this curvature a roofing is- 

 formed over the periphery of the calyx. This is not confirmed by 

 the specimens, in which the calyx is covered by summit plates, in- 

 terradials, etc., and the grooves around the periphery are roofed over 

 by solid covering plates — leaving onl) the lateral margins exposed 

 — in connection with, and forming part of the calicular cavity. The 

 structure is clearly seen in our fig. l!_, PL XIX, in which the grooves 

 are shown open except in one ray, where the covering plates are 

 restored from the same part in another specimen. 



Another figure of Angelin (Tab. VII., fig. 7a) gives an inner 

 view — that is, from below ; not "superne visits," as erroneously stated 

 in the explanation of the plate — of a specimen of C. pulcher of 

 which he speaks as showing the so-called "consolidating apparatus." 



