854 PROCEEDINGS OF THE ACADEMY OF 



larger (y)articulaily longer) as to make the body below the arms always dis- 

 tinctly longer and proportionally narrower. Another marked difference con- 

 sists in the convexity of the body plates, those of longirostris being only slight- 

 ly and evenly convex, while in the form under consideration they are decidedly 

 tumid, and sometimes even angular. The arm-ljases of the loriffiroslris are also 

 more distinctly separated by sinuses, and less robust. In short, the characters 

 mentioned in the species longirosiris impart to it a peculiar and vei'y character- 

 istic neatness and symmetry of appearance not seen in the form here described. 



In form and general appearance our species resembles specimens sometimes 

 supposed to be a broader and more robust variety of ^. subiequaUs, McChesney 

 (sp.), but in that there are four arms to each ray, and the brachial pieces are 

 in close contact all around, while its body plates are not merely tumid, but 

 decidedly tnberculiform and projecting. 



Locality and position. — Lower Burlington beds of the Lower Carboniferous, at 

 Burlington, Iowa. No. 13 of Mr. Wachsmuth's collection. 



Batocrinus trochiscus, M. and W. 



Body broad discoidal or wheel-shaped, being very narrow at the base and 

 widening gradually to the top of the first radials, thence spreading very rapidly 

 to the brachial pieces, which are large and nearly in contact all around, or but 

 slightly separated by small sinuses over the anal, interradial and axillary 

 spaces. Vault flat, or a little concave from the peripherj^ about half-way in 

 toward the middle, thence rising moderately to the subcentral proboscis; com- 

 posed of unequal pieces, the larger of which are rather tumid and arranged in 

 radiating rows coincident with the raj's and their division below, while the 

 smaller pieces between are depressed so as to form concavities between the 

 larger. 



Base narrow, truncated, but not spreading or provided with a distinct rim 

 below, wider than high, and widening very gradually upward. First radial 

 pieces about of the size of the basal, but proportionally longer, though they are 

 generallj' wider than long, two of them heptagonal and three hexagonal. 

 Second radial pieces comparatively very small, and all wider than long, or 

 transversely oblong, being, as usual in this group, regularly quadrangular. 

 Third radial pieces about twice as large as the second, wider than long, and 

 all pentagonal, excepting those of the two posterior rays, one of which is 

 hexagonal and one heptagonal, in the specimen from which the description is 

 drawn up ; each supporting on each of its superior sloping sides, in direct suc- 

 cession, two secondary radials nearly or quite as large as the third primary 

 radials themselves, while each of the upper of these secondary radials is an 

 axillary piece, supporting on each of its sloping sides, in direct succession, two 

 large brachial pieces, thus making four arm-openings to each ray all around, 

 or twenty in the entire series. First anal piece about of the size of the smaller 

 first radials, longer than wide, and heptagonal in form; above this there are in 

 the second range three smaller hexagonal pieces, and, arching over the latter, 

 four in the fourth range, with a small wedge-formed piece succeeding the latter 

 above, though it is scarcely large enough to separate the brachial pieces over 

 the anal area. First interradial pieces nearly as large as the first radials, and 

 all irregularly nine-sided ; above this there are two smaller pieces in the second 

 range, two, or sometimes only one, in the third, and above this one or two 

 succeeding each other in a direct line, the last one being usually narrow, and 

 partly or entirely wedged in between the brachial pieces so as, in some cases, 

 to separate them a little. Between the first divisions of each ray on the third 

 radials there are usually one or two interaxillary pieces, the first resting upon 

 two short sloping upper sides of the first secondarj^ radials, and supjioi-ting the 

 second, which sometimes separates the brachial pieces a little, while in other 

 instances it is so narrow and short as to allow them to come in contact over 

 it, (Arms and columa unknown.) 



[Dec- 



