Siructure o/'CrotalocrinUs. 405 



ment of the calyx-plates in the Crotalocrinid^ as occurs in 

 Forhesiocrinus and in the Ichthyocrinidte generally. 



But if this proof be not forthcoming, Crotalocrinus and 

 Enallocrimis must be removed from the Articulata and assigned 

 to some other group of the Palajocrinoidea ; and as this is a 

 subject which I do not feel myself qualified to discuss, I 

 prefer to leave it to the much more experienced judgment of 

 Messrs. Wachsmuth and Springer. 



There is another point in the structure of Crotalocrinus on 

 which my recent observations at Stockholm enable me to 

 throw some light, or, rather, to correct an erroneous impres- 

 sion which has got abroad. 



On page 12 of the 'Revision,' part i.( 1879), Wachsmuth 

 and Springer wrote as follows : — 



" The so-called ' cousolidatiug-apparatus ' of Capressocrinus is in 

 our opinion a true set of hydrospires, arranged in pairs exactly as 

 in Blastoids, but spreading out horizontally instead of vertically. 

 Angeliu (Icongr. Criu., pi. viii. fig. 7, a, b) figures a Crotalocrinus in 

 which the consolidating apparatus — or hydrospires, as we believe — 

 is most excellently preserved. Even the inner tubes can be traced, 

 and, if there still existed a doubt whether the closely related 

 Cupressocr'mus had its ventral side firmly closed, Angelin's figure, 

 pi. viii. fig. 6, ouglit to remove it. There seems to be in Orotalo- 

 crinus not only^ a solid integument covering the entire ventral disc 

 and inclosing the hydrospires, but we judge from fig. 7 of the pre- 

 ceding plate, that the oral centre or median space between the 

 hydrospires had even a double covering." 



The authors' theory that the consolidating apparatus of 

 Cupressocrinus represents the hydrospires of the Blastoids 

 has since been abandoned, and the explanation of its struc- 

 ture which they have adopted will be found on p. 178 of the 

 * Revision,' part iii. section 2. I have the strongest convic- 

 tion that they will also have to abandon their theory as to the 

 internal hydrospires of Crotalocrinus. They are singularly 

 unfortunate in giving so many wrong references to Angelin's 

 figures of this genus ; for the one on which they rely as 

 proving the existence of hydrospires is on tab. vii., and not 

 on tab. viii., as they state. It is described in the explanation 

 as follows : — " Calyx superne visus, cum parte bracliii, mag- 

 nitudine pauUum aucta. Apparatus quern consolitlantem 

 vocant, intus visus." Jt is to some extent upon this figure 

 that Wachsmuth and Springer's theory as to the existence of a 

 pliable vault in Crotalocrinus was based, foreshadowed, it will 

 be noted, as early as the year 1879. 



Unfortunately, however, the figure represents not the 

 ventral, but the dorsal aspect of the broken calyx, and 

 Ann. & Mag. N. Hist. Ser. 5. Vol. xviii. 28 



