NATURAL SCIENCES OF PHILADELPHIA. 355 



The surface seems to be nearly smooth, or finely granular, and the body 

 plates are nearly even, excepting the secondary radlals, which, M'ith the brachial 

 pieces, are sometimes a little tumid, so as to project slightly beyond the plane 

 of the interradial and iuteraxillary areas, which consequently have a somewhat 

 sunken appearance. 



Height of body to arm-openings, 1 inch ; breadth, 2-10 inches. 



This fine species seems to be most nearly related to B. planodiscus, Hall (sp.), 

 from the Keokuk beds, with which it agrees nearly in form and general appear- 

 ance. It ditfers very materially in structure, however, since the rays in that 

 species bifurcate so as to make eight arm-openings to each ray, or forty to the 

 whole series, being just double the number seen in our species. The planodu- 

 cus also appears to have the arm-openings directed outward, while the species 

 under consideration belongs apparently to the section of this genus with these 

 openings directed upward. 



It is an interesting fact, to which our attention has been called by Mr. 

 Wachsmuth, that not only this species, but several others only found in the 

 very highest part of the Upper Burlington formation, are more nearly allied to 

 species ibund in the Keokuk beds than to any forms iu the Lower Burlington 

 beds. 



Locality and position. — Upper bed Burlington division of the Lower Carbon- 

 iferous at Burlington, Iowa. No. 27 of Mr. Wachsmuth's collection. 



BaTOCBINDS (ErETMOCRINUS ?) NEGLECTUS. 



Body small, inversely campanulate below the arms, and rather ventricose 

 above; the sides expanding gradually from the base to the third radials, and 

 theuce curving out rapidly to the outer edges of the brachial pieces, which 

 are slightly grouped, but nearly or quite in contact all around. Base about 

 three times as wide as high, truncated and concave below, but not thickened 

 or expanded. First radials comparatively large, generally wider than long, 

 and, as usual, two heptagonal and three hexagonal ; all like the other body 

 plates convex, but not properly tumid Second radials much smaller than the 

 first, quadrangular and nearly twice as wide as long. Third radials as long as 

 the second, or slightly larger, wider than long, and all normally pentagonal ; 

 each supporting on each of its superior sloping sides a secondary radial, 

 which in its turn bears on each side above two brachial pieces in direct succes- 

 sion, thus making four arm-openings to each ray, or twenty to the entire series. 

 In one specimen, however, agreeing exactly in other respects, the third radials 

 in the anterior and one in the posterior rays is immediately succeeded by 

 brachial pieces without any further bifurcations, so as to give origin to only 

 two arms to each of these rays ; but this is almost certainly an individual 

 abnormal development. 



First anal plate a little longer, but not otherwise differing from the first 

 radials ; above this there are three smaller pieces iu the next range, and some- 

 times one or two still smaller ones in the third range. Interradial pieces one 

 to three in each space, the first being one-third to one-half as large as the 

 first radials, seven to nine sided, and usually supporting one or two smaller 

 pieces in the second range above. 



Vault convex, and composed of very unequal, irregular, moderately convex 

 plates, provided with a tube or proboscis of moderate thickness, and placed 

 generally about half way between the middle and the anal side. (Column 

 and arras unknown.) 



Height to base of proboscis, about 0-58 inch ; do. to arm-openings, C-33 

 inch ; breadth, 0-55 inch. The specimen presenting the irregularity mentioned 

 iu the arrangement of the arms, is proportionally wider than that from which 

 the above measurements were taken. 



This little species is apparently nearer B. clio, Hall, (sp.), than to any other 

 yet described. Its base, however, is much less thickened and expanded than 

 "in that species, and its body plates more even and smoother ; while its brachial 



1868.] 



