40 



fourth range by four plates that connect with the plates of the 



vault. There is some irregularity in the last range of plates and 

 two of them are elongated and in part belong to the vault. The 

 fact is, that there is no line directly separating the plates of the 

 calyx, in this area, from those belonging to the vault. 



Vault abruptly convex on the azygous side and highly con- 

 vex on the other, so that the vault has two or three times the 

 capacity of the calyx. The vault is not depressed in the in- 

 terradial areas, but carries its convexity full to the margin of 

 the interradial areas of the calyx. It is covered witli large 

 polygonal nodose plates and bears a large, subcentral probos- 

 cis. 



The expanded basals and large subcentral proboscis will 

 cause it to be classed witli Eretmocrinus, by many authors. 

 The union of the interradial areas with the vault is not a com- 

 mon character of Batocrinus, but this is not a special charac- 

 ter ascribed to Eretmocrinus, and if it were, still it is a char- 

 acter jiossessed by many species of Baiocrinus. On the whole, 

 the quadrangular second primary radials ally it with Bato- 

 crinus so strongly, that we have no hesitation in referring it 

 to that genus. It is in striking contrast with the Baiocrinus 

 figured on Plate I of this Bulletin, and shows the wonderful 

 development of this genus. This species is distinguished from 

 B. yandelli, which it most resembles, by having twenty-five 

 instead of twenty-one or twenty-two arm openings to the vault, 

 and by having one more regular interradial in each area and 

 one or two more azygous plates. The calyx is not as high, 

 though it is a larger species. 



Found by Geo. K. Greene, in the Keokuk Gi-oup, at Button 



Mould Knob, Kentucky, and now in the collection of Wm. F. 



E. Gurley. 



8HX'MARDOCRiNUS, n. gen. 



This genus is founded upon the species described by Shumard, 

 under tlie name ef Aclinocrinns concinnus, in the Geo. Sur. of 

 Mo. for 1H55, page 1H9, and illusti-ated on plate A, figure 5. 

 The generic formula is as follows: Basals, 3. Radials, 2 by o. 

 Regular interradials, 1. Azygous interradials, 3. Interradial 

 areas connect with the vault without any distinguishing line of 

 separation. Azygous orifice subcentral. No proboscis. Type 

 Shiimardocrinus concinnus. 



Th8 specific description given below may embody generic 

 characters, but as we have only one species belonging to the 

 genus, it is not easy to distinguish characters that are specific 



