BATOCRINIDZ. 503 
species, in which they meet at an angle. Arms very long and heavy, less 
tapering than usual in this genus. First interbrachial large, subovate, the 
upper end curved, rising to one fourth the height of the arm facets; it 1s 
followed by two or three smaller, elongate pieces, of which the third, when 
present, is wedged in from above between the other two, frequently without 
touching the first plate. First anal higher and narrower than the radials, 
supporting a second anal and two rather large interbrachials, Ventral disk 
strongly inflated at the anal side, the anal opening directed upward, located 
in the middle of a flattened area, which extends beyond the summit of the 
posterior oral, making that side of the disk lean out of a perpendicular be- 
yond the line of the dorsal cup. The plates in the lower part of the tegmen 
are perfectly flat, some of the upper ones slightly elevated, but not nodose, 
except the posterior oral. This plate which is extremely large and excentric, 
is pushed with the other orals to the anterior side, and stands erect, forming 
a part of the lateral walls of the calyx. The radial dome plates cannot be 
distinguished from the interambulacrals, and probably in some cases were 
not exposed atall. Interambulacral plates quite numerous, especially on the 
anal side. Column rather large, the nodal joints a little wider and with 
rounded edges. 
Horizon and Locality. — Upper Burlington limestone, Burlington, lowa. 
Type in the White collection in the University at Ann Arbor. 
Remarks. — The enormous inflation of the posterior side, making the 
whole calyx sometimes appear to lean to one side, the excentricity of 
the orals, and the flatness of all the plates, distinguish this species quite 
readily from all others of the genus. 
Agaricocrinus planoconvexus Hatt. 
Plate XX XVIIT. Figs. 6a, b, c. 
1861.  Agaricocrinus planoconvecus —Hati; Prelim. Deser. Paleoz. Crin., p. 3. 
1861. Agaricocrinus (Amphoracr.) planoconverus — Hatt; Bost. Journ. Nat. Hist., Vol. VII., p. 280. 
1870. Amphoracrinus planoconvexus —S. A. MituER; Catal. Amer. Paleeoz. Foss., p. 70. 
1881. <Agaricocrinus planoconverus —W. and Sp.; Revision Paleocr., Part IL, p. 112. 
Syn. Agaricocrinus decornis RowLEy and Hare, 1891, Kansas City Scient., p. 117, Plate 3, Fig. 10. 
Syn. Agaricocrinus Blairi S. A. Minter; 1892, Adv. Sheets 18th Rep. Geol. Surv. Indiana, p. 21, 
Plate 3, Figs. 12, 13, 14. | 
This species probably has its closest affinities with A. inflatus, but its 
calyx is smaller, proportionally shorter — the height and width being as 3 to 
§ — and less inflated at the posterior side. It is distinctly pentangular in a 
