84 PROCEEDINGS OF THE ACADEMY OF [1887. 



White; and we ^ in 1881 gave a figure of the sunwnit covering in 

 Schizoblashis ( Granatocrinus) Sayi. 



In 1858, Shumard " described what he took to be a somewhat 

 similar covering in a sjiecimen of Pentremites conoideus, which he 

 figured and described as having the central stelliform space (mouth) 

 "perfectly closed by six small, microscopic plates, a central one of 

 a pentangular form surrounded by five smaller pentagonal pieces, 

 which unite with the edges of the aperture and form a little dome. 

 The five ovarial openings are each, in like manner, closed, as 

 represented in the figure by six minute polygonal plates, so arranged 

 as to form a little elevation." Shumard's description of P. conoideus 

 was endorsed by Billings^ who copied his figure, but modified it by 

 adding a small pore at each of the five angles, through which, as he 

 thought, the ambulacra entered the interior. 



The fact of the closure of the summit ojiening in the above 

 mentioned species, and in Pentremites generally, has on the other 

 hand been denied by Dr. Hambach,^ who states that the central 

 opening "was never closed by additional plates, as intimated by 

 some authors (Billings and Shumard), although specimens are 

 frequently found (and I have some in my collection) where it 

 appears as if the summit were closed by additional plates, which, on 

 close examination, however, prove to be Bryozoa or ovulum-like 

 bodies." In a subsequent paper he ^ says that Shumard's original 

 specimen of P. Sayi, which was figured in the Missouri Report, 

 "proves to have only a covering of minute calc-spar crystals on the 

 summit, leavings of the surrounding luatrix, which could easily be 

 removed by applying a moist camel's hair brush to them;" and he 

 adds "my specimens which shoAV such a covering * * * prove that 

 the covering consists only of fragments of broken up pinnulae which 

 were washed into the ambulacral furrows and remained there." 



As to Hambach's general statement that the central opening was 

 never closed by additional plates, he has undoubtedly been misled 

 by the condition of his specimens. We are certain that if he were 

 to examine the numerous specimens in our collection of Schizohlastus 

 Sayi, Granatocrinus Norwoodi, G. melo, OropJiocrinus stelliformis, 



5 Revision of the Palaeocrinoidea Pt. II, PI. XIX, fig. 3. 



6 Trans. St. Louis, Acad. Sci. 1858, Vol, I No. 2, p. 243. 

 J Amer. Journ. Sci. 1869, Vol. XLVIII, p. 82. 



2 Trans. St. Louis, Acad, Sci., 1880, Vol. IV, p. 150. 



3 Tr.ins. St. Louis, Acad., Sci., 1884, Vol. IV No. 3, p. -540. 



