68 CATALOGUE OF THE BLASTOIDEA. 



E/cvaerinus. But he is altogether silent upon this point, and does not venture to 

 call the plates in question either ovulum-like bodies or Bryozoa. As regards Pen- 

 tremites eonoideus, however, he is in no doubt whatever, and is convinced that the 

 summit-plates in Shumard's specimen are merely " ovulum-like bodies; " but to use 

 his own expression (though with a change of names), we think that Dr. Shumard 

 " deserves as much confidence as " Mr. Hambach, both in the case of Pentremites 

 eonoideus and in that of Schizoblastus Sayi. 



It may be well to mention here that Shumard's figure was copied by Billings l , 

 who from his own observation of a similar example of the same species, added to it 

 what he called "a small pore in each of the five angles of the central aperture; 

 the five ambulacral grooves enter the interior through these pores." The latter 

 statement is correct enough, for the pores are, so to speak, the openings of the 

 ambulacral tunnels beneath the vault, such as are shown in our figures of Grana- 

 tocrinus Nonvoodi (PI. VII. fig. 13) and of Elceacrinus Verneuili (PI. XVIII. fig. 16). 

 They correspond precisely, as Billings pointed out, to the ambulacral openings of the 

 true Crinoids, and to the ambulacral, or, as he preferred to call them, the ovarian 

 pores of Caryocrinus. He also applied the latter name to these pores in Pentre- 

 mites eonoideus, as he had adopted White's theory of the ova being germinated 

 within the body, and passing out through the central aperture and down the 

 ambulacral grooves to the pinnules. We now know, however, that this is altogether 

 incorrect, and that the ovarian pores of Billings are merely artificial openings caused 

 by the removal of the covering plates from the ambulacral grooves, as is well seen 

 in PI. I. fig. 8, PL III. fig. 3, and PL XV. fig. 12. 



Some eight years after the appearance of Shumard's Missouri Report, his obser- 

 vations upon the closure of the summit in Granatocrinus Nonvoodi by a group of 

 small plates was confirmed by White 2 , who described the peristome as being " over- 

 laid with an integument of microscopic plates, entirely covering the central aperture, 

 passing out between the bases of the tubes in a double series of plates." This is 

 well shown in PL VII. figs. 4, 13, more especially in the latter figure. White 

 further discovered essentially the same summit-structure in Oroj)hocrinus stelli- 

 formis 3 . The proximal ends of the food-grooves are " neatly filled by a compound 

 series of minute plates, which closely connect at the summit with five small plates, 

 arranged like a five-pointed star, with the points touching each of the upper ends 

 of the interradial plates, thus completely covering the summit-aperture, which 

 weathered specimens show to exist beneath." 



Mr. Wachsmuth has lent us an example of this species which shows these 

 characters very well (PL XV. fig. 12), though the five central plates do not seem to 

 be arranged quite as regularly as in that described by Dr. White. His observations, 



i American Jouni. Sci. 1869, vol. xlviii. p. 81, fig. 1") ; Ann. & Mag. Nat. Hist. 1870, vol. v. pp. 264, 265. 

 2 Boston Journ. Nat. Hist. 1863, vol. vii. no. 4, p. 484. 3 Ibid. p. 487. 



