42 Trans. Acad. Sci. of St. Louis. 



greater than in 0. roemeri. Cribrohlastus roemeri 

 is much rarer than C . sampsoni. 



*14. Cribkoblastus sayi, Shumard. Burlington limestone. 



Pentremites sayi, Shumard. 



Granatocrinua sayi, Shumard. 



Schizohlastus sayi, Etheridge and Carpenter. 



Schizoblastus potteri, Etheridge and Carpenter. 



My species C. potteri has been taken as synonym 

 for C . sayi. The interambulacrum of C . sayi is 

 broader and transversely striated and more elevated 

 than in C . potteri. The base portion in O. sayi 

 is depressed so that the basal part is not visible in a 

 lateral view, which is the case in C . potteri. The 

 slit-like openings at the summit in both species, as 

 well as in C . melonoides, are due to the ambulacral 

 integument in the immediate neighborhood of the 

 genital openings. The perfectly round form of the 

 genital openings can be sufficiently proved in weath- 

 ered specimens, where the ambulacral integument is 

 eroded. Moreover it seems that this species is very rare 

 at Burlington, as of all specimens coming from that 

 locality, I have not noticed more than a dozen typical 

 specimens. Shumard' s type specimen came from 

 Marion County in the neighborhood of Palmyra. It 

 also occurs in Boone County, St. Louis County, and at 

 Louisiana, Missouri. 



15. Cribkoblastus shumardi. Meek and Worthen. Bur- 

 lington limestone. 

 Granatocrinxis shnmardi, Meek and Worthen. 

 Mesoblastus shumardi, Etheridge and Carpenter. 

 Schizoblastus shumardi, Etheridge arid Carpenter. 



For difference of those species marked with an aste- 

 risk, see Plate V., Fig. 9, 10, 11, 12, 13, 14, 15. 



3. Genus Saccoblastus. 



General form of the body pyriform, compressed cylindri- 

 drically, or club-shaped. Ambulacra narrow and linear, gen- 



