the Crinoidea, Cjstidea, and Blastoidea. 255 



with the ambuhicral pores at their bases, are Crinoidal cha- 

 racters. 



In addition ty the above, the following s})ecies may be re- 

 ferred to as examples of Crinoids with the mouth separate 

 from the centre of the radial system : — 



Amphoracrmus tessellatus (Phillips). Figured by J. Rofe, 

 Esq., Geol. Mag. vol. ii. p. 8, fig. 3. The figure represents a 

 cast of the interior of the vault, showing the five ambulacral 

 grooves in relief. The mouth is situated in the angle between 

 tiie two anterior grooves. 



Stwtocrinus perianbrosus (Hall, sp.). Figured by Meek and 

 Worthen in the ' Geology of Illinois,' vol. ii. p. 188, f. 5. 

 The specimen is 13 lines in diameter, the ambulacral centre 

 13 lines from the anterior margin, and the mouth 11 lines*. 



Ghjptocrinus armosus (M'Chesney, sp.). This extraordi- 

 nary Crinoid is figured by M'Chesney in his '■ New Pal. Foss.' 

 pi. 7. f. 6, and also by Prof. Hall, in the 20th Reg. Pvep. N. Y. 

 pi. 10. f. 11. The specimens are between 2 and 3 inches in 

 length. There are ten arms; the anterior side is much inflated; 

 the proboscis appears to be large at its base and excentric in 

 its position, but, instead of standing erect, it bends down to 

 the surface of the vault, and lies upon it, crossing over to the 

 posterior margin. Judging from the figures, the centre of the 



* In April last I receivecl from Messrs. Meek and Worthen a paper 

 entitled ''Notes on some points in the Structure and Habits of the Palajo- 

 zoic Crinoidea." Of all the papers relating to this subject yet published 

 on this continent, this one (at least, so it appears to me) is the most in- 

 teresting and important. It is written with a clearness and particularity 

 rarely to be seen in palreontological memoirs. In some respects it con- 

 firms the opinions advocated in these notes, but bears directly against 

 my views on the question here under discussion, i. e. " the position of the 

 mouth with relation to the radial centre." As I wish to give the remark- 

 able observations of the authors full consideration, I shall not discuss 

 them now, but delay until the September No. of this .Journal. [Meek 

 and Worthen's paper is given in Silliman's Journal, July 18(39, p. 23.] 

 I shall only state here that I believe that the grooves on the ventral disk 

 of Cyathocrinus, and also the internal '■^ convoluted plate"' of the palteozoic 

 Crinoids, with the tubes radiating therefrom, belong to the respiratory 

 and perhaps, in part, to the circulatory systems — not to the digestive 

 system, as is supposed by the authors. The convoluted plate, with its 

 thickened border, seems to foreshadow the " oesophageal circular canal," 

 with a pendent madreporic apparatus as in the Ilolothuridea. To me the 

 final determination of this question is of much importance ; for if Meek 

 and Worthen are right, then I must be wrong so far as regards nearly all 

 that I have published with reference to the functions of the apertures of 

 the paheozoic Echinodermata. It is fortunate that the solution of this 

 curious problem is now undertaken by men who have access to the mag- 

 uiticent cabinets of the geologists of the western States, and also by men 

 who habitually discuss scientific subjects with the sole object in view of 

 arriving at the truth. 



