22 Trans. Acad. Sci. of St. Louis. 



the reader, I will recapitulate the various views of our most 

 distinguished palaeontologists concerning this question, which 

 will show that very little attention was given to anatomical 

 differences, and that all specimens enumerated in this genus 

 were placed there on merely external resemblances. If anat- 

 omical differences had been considered, Shumard would never 

 have proposed to put species like Gr^anatocrinus norwoodi, 

 curtus, granulalus, sayi, roemeri, cornutus, etc., into one 

 genus* 



In 1861, Meek and Worthen say, in speaking about Pen- 

 tremites cornutus and Pentremites melo:] *' Both of these 

 forms differ from the typical species of the genus Pentremites 

 in having each pair of ovarian openings distinctly separated, 

 instead of closely united with merely a thin septum between. 

 In this character, as well as in form, and the prolongation of 

 the pseudo-ambulacral areas, they agree with the genus 

 Nucleocrinus of Conrad (^ = Elaeacrinus , Roemer), from 

 which they differ in having the anal and oral openings dis- 

 tinct as in the true Pentremites. They constitute a sub- 

 genus of Pentremites, occupying a position between the 

 typical forms of that genus and Nudeocrinus.'' 



In 1862 Prof. Hall says in speaking about the genus Nu- 

 cleocrinus: X — 



'* Regarding only the general form of these bodies, this 

 genus would include several species, heretofore described 

 under Pentremites, from the Carboniferous limestones of the 

 Western States, viz. : Pentremites norwoodi, Owen and 

 Shumard; Pentremites melo, Owen and Shumard; Pentremites 

 curtus, Shumard, and others; while the Pentremites (^Olivan- 

 ites) verneuili = Elaeacrinus verneuili, Eoemer, and Olivan- 

 ites angularis, Lyon, are of the age of the upper Helder- 

 berg limestones ; and the JSTncleocrinus elegans, Conrad, and at 

 least one other species, occur in the Hamilton group. The 



♦ Boemer^s Pentremites granulatus is taken as type of the geuus. — See 

 B. F. Shumard, Transactions of The Academy of Science of St. Louis, Vol. 

 II., p. 375. 



t Proceedings of The Academy of Natural Sciences of Philadelphia, 1861, 

 p. 142. 



X Fifteenth Annual Report of the Regents of the University of the State 

 of New York, p. 145. 



