54© TRANS. ST. LOUIS ACAD. SCIENCE. 



of the integument so that the parallel running plicas are bent to 

 a sigmoid form without making any of the sutures between lancet 

 and poral pieces visible, while, if they were only surface ornamen- 

 tations, they w^ould appear in a right angle opposite to each other 

 and showing the sutures. Or, how would Mr. Carpenter explain 

 the presence of those large and strange bodies in the interior of 

 the calyx, which are frequently found in entirely perfect and 

 undisturbed bodies^ if the acute points of the integument were 

 not flexible? Such and similar specimens, I should think, would 

 afford sufficient proof of the correctness of my assertion. 



" It is very singular," says Mr. Carpenter, that I do not "make 

 the slightest mention of the minute plates which have been de- 

 scribed by so many authors as covering in the ambulacral furrows 

 of the Blastoids." It is true I did not speak about them, for the sim- 

 ple reason that I always found them in such a form, or condition, 

 as to make on me the impression that they were mere accidental 

 coverings, nor- did I see any good reason for their presence. 



Shumard's original specimen of Pentremites 6'«y^', which was 

 figured by F. B. Meek,* and is now in the collection of the Wash- 

 ington University, proves to have only a covering of minute calc- 

 spar crystals on the summit, leavings of the surrounding matrix, 

 which could easily be removed by applying a moist camel's- 

 hair brush to them. The specimen figured by Mr. Wachsmuth.f 

 also a representation of the above-named species (according to 

 his statement), is not reliable, as Shumard's description of Pen- 

 tremites Sayi differs very materially from that represented by 

 him ; but, as both are to represent one and the same species, 

 one must necessarily be an incorrect one, and in this respect I 

 think Prof. Meek deserves as much confidence as Mr. Wachs- 

 muth. My specimens, which show a similar covering as in this 

 last named figure, prove that the covering consists only of frag- 

 ments of broken-up pinnule which were washed into the ambu- 

 lacral furrows and remained there. 



The minute plates of Pentremites conoideus described and fig- 

 ured by ShumardJ are copied by Billings, § with only the ovarian 

 pores added to it (according to Billings' own statement). The 



* G. C. Swallow, Geol. Survey of Missouri, iSss, PI. B, Fig. i c. 



t Palaeocrinoidea, Ft. ii., 1881, PI. xix.. Fig. 3. 



% Trans, of the Academy of Science of St. Louis, vol. i., 1S56-60, Pi. 9, Fig. 4. 



§ Loc. cit. p. 102, Fig. 63. 



