BATOCRINID^. 593 



species, in which they meet at an angle. Arms very long and heavy, less 

 tapering than usual in this genns. First interbrachial large, subovate, the 

 upper end curved, rising to one fourth the height of the arm facets ; it is 

 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 at all. Interambulacral jjlates 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, Iowa. 



Type in the White collection in the University at Ann Arbor. 



Bemarks. — 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 Hall. 

 Plate XXXVIII. Figs. 6a, h, c. 



1861. Jffamomms planoconvexus — Ball; Prelim. Descr. Palteoz. Crin., p. 3. 



1861. Agaricocrinus (Jnipkoracr.) planoconvexus— Hall ; Bost, Journ. Nat. Hist., Vol. VII., p. 280. 



1870. Ar,iphoracrinusplanoconveX2is — S,. A. Millee ; Catal. Amer. Pateoz. Foss., p. 70. 



1881. Af/aricocnnus planoconvexus — ^. and Sp. ; Revision Palffiocr., Part IP, p. 112. 



Syn. Agaricocrinus decornis RoifLET and Hare, 1891, Kansas City Sclent., p. 117, Plate 3, Fig. 10. 



Syu. Agaricocrinus Blairi S, A. Millek; 1892, Adv. Sheets IStli Rep. Geol, Surv. Indiana, p. 21, 

 Plate 3, Figs. 12, 13, 14. 



This species probably has its closest affinities with A. iiiflatus, but its 

 calyx is smaller, proportionally shorter — the height and width being as 3 to 

 5 — and less inflated at the posterior side. It is distinctly pentangular in a 



