208 NEW YORK STATE MUSEUM 



(in a collapsed state, it is true) through all the ages of the Car- 

 bonic period and the present time." ^ We must regard criticism 

 of this character as at least unfortunate. In New York State 

 Museum Bulletin 107, page 106, I have given reasons for believing 

 that the inner edges of the hydrospires were membranous at death, 

 yet their carbonized outlines have remained, and for the greater 

 part in their original position, from Chazy time to the present. 

 Traces of just such membranes will be noted in the description of 

 Palaeocrinus striatus Bill, on p. 218 of the present 

 paper. The more difficult the field in which one is working, the 

 greater is his liability to error. If one is made to feel that it is 

 a disgrace to err at all in such a field and that any admittedly 

 speculative matter will receive censure, it can only follow as a 

 consequence that very much valuable observation and suggestion 

 will die with the mind of the worker and perhaps not appear 

 again for centuries. Encouragement to work in such difficult 

 fields is what is needed. Cross-fertilization of mind followed by 

 just and searching criticism will bear only good fruit. Ham- 

 bach is very probably correct in attributing the structures repre- 

 sented in plate 2, figure i of his *' Revision " to collapsed mem- 

 branes in the poral openings. That they were " tentacles," how- 

 ever, is exceedingly doubtful. We may, I believe, accept Doctor 

 Carpenter's contention that the mouth, food grooves and pores 

 were covered with small but well fitting plates. With this cov- 

 ering we have all the essentials of a food-capturing and respira- 

 tory system very similar in nature to that here presented for 

 Blastoidocrinus. 



ADDITIONAL REMARKS ON BLASTOIDOCRINUS 



From various other points of interest connected with this 

 Canadian type we may select that concerning the penetration 

 of the stem so far into the interior of the theca. Billings be- 

 lieved ^ that the position shown in our plate 4, figure i, was 

 a natural one. A careful examination of the type convinced me 

 that an additional portion of the stem was still to be found below 



1 Ann. and Mag. Nat. Hist. scr. 5, 8:423. 



2 In Canadian Org. Rem. Dec. IV, p. 21, Billings says " the column actu- 

 ally penetrates into the interior, nearly if not quite to the top of the visceral 

 cavity. This is so extraordinary a structure that scarcely any paleontologist 

 at all well acquainted with the organization of the Crinoidcae could be 

 brought to believe it without personal inspection of the proofs." 



