31 



lateral angles of the first radials, in that species, are truncated 

 and stand upright, while in this species, they curve in over the 

 margin of the vault and are not truncated. The facets for the 

 second radials are proportionally much smaller, in that species, 

 than they are in this, which indicates differences in the construc- 

 tion of the arms. As these differences in the construction of the 

 calyx must rank as of specific importance, the surface ornamenta- 

 tion may also be uspd to distinguish the species. 



Found in the Keokuk Gi'oup, at Keokuk, Iowa, and now in 

 the collection of Wm. F. E. Gurley. The specific name is in 

 honor of D. G. Anderson, of Keokuk, Iowa, from whom this 

 specimen was obtained. 



CYATHOCKINUS TUMIDULTIS, n. sp. 



Plate III, Fifr. 7, vievf opposite the azygous side. Sppcimeu some- 

 what fattened and the ends of the arms broken away. 



Species medium size and bearing very heavy arms. Calyx low, 

 basin shaped; sutures depressed; surface granular. 



Basals small and apparently hidden by the column in the 

 concavity of the lower side of the calyx, though, as our speci- 

 men is depressed, it is probable that the basals may be seen in 

 a better specimen extending slightly beyond the column. Sub- 

 radials large and remarkably tumid, being roughly hemispheri- 

 cal externallv. First radials a little smaller than the subradials, 

 tumid, transversely angular in the middle part and truncated 

 the entire width above. Second radials quadrangular, trans- 

 versely angular in the middle part, and more than twice as 

 wide as high. Third radials in four of the j-ays pentagonal, 

 axillary, and supporting upon each of the upper sloping sides a 

 single arm. The ray opposite the azygous area' consists of a 

 single arm, which commences on the first radial ivith a quad- 

 rangular plate as in the other series. This gives to the species 

 only nine arms. 



The first azygous plate truncates a first radial and extends 

 nearly as high as the first radials, and has a short upper side 

 on which rests a smaller plate. 



Arms long, coarse, rough, and composed of short, more or 

 less cuneiform plates, projecting on alternate sides above for 

 the reception of short, stout pinnules. 



