188 Trans. Acad. Sci. of St. Louis. 



which give origin to successive rows of minute spines. 

 Length of an average specimen 9 mm., width 10 mm., and 

 thickness 6 mm. 



Remarks. Among the specimens used by White for the 

 description of Athyris crassicardinalis, three distinct species 

 belonging to there different genera were included. Eleven out 

 of the sixteen type specimens are members of a species char- 

 acterized by a peculiar transversely flattened brachial valve 

 and which shows no indication of the concentric rows of 

 spines mentioned in the original description as being present 

 in some specimens. These nine specimens have been retained 

 as the typical form of Athyris crassicardinalis. One of the 

 five additional specimens is a member of the species Niicleo- 

 spira barrisi, and four remaining specimens seem to be identi- 

 cal with VJeiothyris hirsuta, first described from the Spergen 

 Hill fauna in Indiana, of St. Louis age. It is upon these 

 specimens alone that the fringes mentioned by White are 

 sometimes preserved. These specimens from theKinderhook 

 oolite at Burlington, are so nearly like many of those from 

 St. Louis oolite of Indiana, both in size, form and manner of 

 preservation, that were specimens from the two localities 

 mixed together it would be impossible to distinguish them. 

 It is quite possible that all these shells, along with other some- 

 what larger ones from the Osage faunas, should be considered 

 as being but variations of Gleiothyris roissyi. 



Spirifer marionensis Shum. 



PI. XVI. f 16-17. 



Shell subcircular or subsemielliptical in outline, from one- 

 half to two-thirds as long as broad, the valves subequally con- 

 vex, the cardinal extremities usually mucronate in the younger 

 individuals, but becoming less pointed in the older specimens. 

 Pedicle valve with the greatest convexity posterior to the 

 middle, umbo prominent, beak pointed and incurved ; the 

 sinus well defined, narrow and angular at the beak, becoming 

 broad, shallow and less well defined toward the front, marked 

 by three or four dichotomizing plications ; cardinal area of 

 moderate height, the sides subparallel, the delthyrium rather 

 broadly triangular. Brachial valve regularly convex, flat- 



