372 PALEONTOLOGY OF ILLINOIS. 



proboscis, 1.07 inch; greatest breadth (at arm-bases), 1.20 

 inch. 



This species is perhaps most nearly allied to B. longirostris, Hall 

 (sp.), and if we suppose the presence of only three arm openings in one 

 of its anterior lateral rays to be abnormal, which is almost certainly 

 the case, it would present no difference in its arm-formula, nor any 

 marked difference in the details of its structure, excepting in the pro- 

 portional sizes of certain plates. This latter character, however, im- 

 parts a material difference to the whole form of the body a difference, 

 indeed, that is so striking as to be apparent at a glance. For instance, 

 in B. longirostris the first and second primary radials and first anal, as 

 well as the first interradial pieces, are all proportionally so much larger 

 (particularly longer) as to make the body below the arms always dis- 

 tinctly longer and proportionally narrower. Another marked difference 

 consists in the convexity of the body plates : those of longirostris being 

 only slightly and evenly convex, while in the form under consideration 

 they are decidedly tumid, and sometimes even angular. The arm-bases of 

 the longirostris are also more distinctly separated by sinuses, and less 

 robust. In short, the characters mentioned in the species longirostris 

 impart to it a peculiar and very characteristic 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 B. subce- 

 qualis, 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 tuberculiform and project- 

 ing. 



Locality and position Lower Burlington beds of the Lower Carbon- 

 iferous, at Burlington, Iowa. No. 13 of Mr. WACHSMUTH'S collection. 



BATOCBINUS TEOCHISCUS, M. and W. 



PI. 5, fig. 6 

 Batocrinus trochiscus, MEEK and WORTHEN. Proceed. A cad. Nat. Sci., Phila., 1868, p. 354. 



BODY broad, discoidal or wheel-shaped, being very nar- 

 row 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, inter- 

 radial and axillary spaces. Yault flat, or a little concave 

 from the periphery about half-way in toward the middle, 



