NATURAL SCIENCES OF PHILADELPHIA. 353 



tinguished by its much more depressed form, particularly below the arm-open- 

 ings, caused by its much shorter basals, and first and second radial pieces. Its 

 base also differs in being much more excavated, and not near so expanded be- 

 low, while its brachial pieces are proportionally stouter, and more crowded. 

 Although the whole number of arm-openings is the same in these two forms, 



4 



this arrangement is different, the formula of B. pistillus being 5-0 ::=24, and 



0—5 



that of the form under consideration 4-— 1 = 24. 



Locality and position. — Lower division of Burlington beds of Lower Carbon- 

 iferous at Burlington, Iowa. No. 14 of Mr. Wachsmuth's collection. 



Batocuinus Cassedayanus, M. and W. 



Body rather broad subturbinate below, or with the vault subglobose, being 

 a little larger below than above the arm-bases. Base short, or about four times 

 as wide as high, a little thickened, and slightly overhanging the end of the 

 column, and more or less notched at the sutures, so as to present a somewhat 

 trilobate appearance. First radial pieces of moderate size, and, like all of the 

 other body plates, rather distinctly tumid, wider than long, two hexagonal and 

 three heptagonal. Second radials about half as large as the first, nearly twice 

 as wide as high, normally quadrangular, but some of them occasionally with 

 one or both of the superior lateral angles a little truncated, so as to present an 

 irregular pentagonal or hexagonal outline. Third radials sometimes a little 

 smaller, and in other rays a little larger, than the second; all pentagonal, and 

 (excepting in the anterior and one of the anterior lateral rays of the typical 

 specimen) each supporting on each of its superior sloping sides, in direct suc- 

 cession, two secondary radials, generally of near its own size, the upper ones 

 of which are also axillary pieces, and bear on each of their superior sloping 

 sides two brachial pieces in direct succession (the last of which is generally 

 larger than the first), thus making four arms to each of these rays. In the an- 

 terior ray, however, the third radial merely bears on each side above, three 

 brachial pieces in direct succession, and the same is also the case on one side 

 of one of the anterior lateral rays, thus only giving origin to two arm-openings 

 in the first, and three in the latter, making seventeen arm-openings to the en- 

 tire series. First anal of the same size and form as the first radials, excepting 

 that it is proportionally a little longer ; above this there are three smaller 

 pieces in the second range, three in the third, and two or three in the fourth. 

 First interradials of the same size as the second anals, hexagonal or heptago- 

 nal in form, and supporting two smaller pieces in the third range, with two to 

 three or four still smaller pieces above, the upper one of which, like that of 

 the anal series, separates the brachial pieces a little, so as to form a small sinus 

 between the arm bases belonging to each ray. 



Vault slightly ventricose, composed of very irregular, unequal, merely tumid 

 pieces, and j)rovided with a rather stout, nearly central proboscis, which is in- 

 clined a little forward in the typical specimen. 



The specific name is given in honor of Mr. S. A. Casseday, deceased, the 

 author of the genus Batocrinus. 



Height of body to arm-bases, 0-70 inch ; do. to base of proboscis, l-OT 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 pre- 

 sent no difference in its arm-formula, nor any marked difference in the details 

 of its structure, excepting in the proportional sizes of certain plates. This 

 latter character, however, imparts 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 



1868.] 



