15 



balloon -shaped bulb, that has the azygoiis openino: at one side 

 of the summit. The plates of the vault are plain, or slightly 

 convex, and smooth, but each plate, on the central and lower 

 part of the balloon, bears a central tubercle, while the small 

 plates on top and s\irrounding the orifice are smooth. 



This species will be distinguished by the arrangement of its 

 sixteen arms, by the four plates in the azygous area, and by the 

 balloon -shaped proboscis. The sha]ie of the vault and probos- 

 cis, in this genus, varies so much, that it may be doubtful 

 about how far its form may be regarded as of even specific 

 importance. We have among the species herein described the 

 long slender proboscis extending beyond the arms, the balloon 

 shaped proboscis, with arms capable of spreading all over it, 

 and the convex vault, without pi'oboscis, save a swelling area 

 like a recumbent jiroboscis, with the azygous orifice below the 

 ambulacral canals. The breaking up of the genus Batocrinus, 

 on characters, based on the vault, azygous orifice, and superior 

 part of the arms, into subgenera or distinct generic names does 

 not seem to be practicable or natural. 



Found in the Keolfuk Group, at Boonville, Missouri, and now 

 in the collection of S. A. Miller. 



BATOCRINUS BROADHEADI, n. SJl. 



Plnle /, Fig. 10, htnil view az'jgous side up; Fig. It, view 

 opposite the azi/gous area. 



Species full medium size and among the larger forms with 

 which it is associated. Calyx somewhat hemispherical, in gen- 

 eral outline, rather more than twice as wide as high; radial 

 series forming low, angular ridges from the basal jilates to the 

 free arms; interradial areas gently rounded; arm openings 

 directed nearly horizontally; sutures distinct; surface granular. 



Basals form an hexagonal disc that expands a little beyond 

 the angles of the radial ridges, and has a diameter two and a 

 half times the diameter of the column, and a hemisphei-ical 

 depression in the truncated surface below, for the attachment 

 of the column. First primary radials twice as wide as long, 

 longitudinally angular in the central part. Second jirimary 

 radials quadrangular, and varying from one and a half to two 

 and a half times as wide as long. Third primary radials pen- 



