BATOCRINID^. 395 



at the posterior side, where there are three in the first row, and two or three 

 in the second. Ventral disk never as high as the dorsal cup, and in some 

 specimens fully one fourth smaller. Posterior oral and radial dome plates 

 more prominent and larger than the surrounding plates. Anal tube moder- 

 ately large and subcentral. 



Horison and Locality. — Lower Burlington limestone ; Burlington, Iowa. 



Types in the Museum of Comparative Zoology. 



Eretmocrinus calycvdoides (Hall). 

 Plate XXXIV. Figs, la, b, B, 3, 4. 



I860. Actinocrinus mlycuhides — Hall; Suppl. Geol. Rep. Iowa, p. 17 ; Ptotogr. Plate Sc, Pigs. 2, 3, 4 



(N. York State BuU. No. I.). 

 1873. Batocriims {Eretmocrinus) calt/culoides — Meek and Wouthes ; Geol. Kep. Illinois, Vol. V., p. 368. 

 1881. Eretmocrinus calyculoides — W. and Sf. ; Revision Palseocr., Part II., p. 172. 



Calyx below medium size, depressed subpyriform, as wide as high. 

 Dorsal cup obconical, truncate at the base, the sides gradually expanding 

 from the top of the basals to the height of the first palmars, whence it 

 spreads abruptly outward so as to place the arm bases at right angles to 

 the diameter of the calyx. Plates flat, the surface devoid of ornamentation, 

 and the suture lines obscure. 



Base short, slightly lobed ; the lower end somewhat projecting and form- 

 ing a sharp edge ; the lower face flat, except the median part which is mod- 

 erately excavated for the reception of the column. Eadials almost twice 

 as large as both costals together, nearly as long as wide ; the upper face 

 concave. Distichals 3 X 2 in the anterior ray, and two arms ; the other 

 rays have 2X2 distichals, followed by two palmars and four arms. Palmars 

 in contact laterally, very short, and curved like free arm plates, having a 

 deep sulcus at each side. Arm facets proportionally large, lunate, directed 

 outward, and arranged in groups, there being wider interspaces between the 

 rays than between their subdivisions. Arms long, incurving, and biserial 

 from their bases up. To the height of about 3 cm. they are subcylindrical, 

 when they grow flat and widen gradually, reaching at two thirds their 

 height a width of about 6 to 7 mm., which in the upper portions is reduced 

 again to 3 mm. The arms in the flattened parts, up to their tips, are 

 knife-like, sharp at both sides, and serrated along the edges ; the plates are 

 short near the calyx, but increase to more than twice their length as the 

 arms flatten out. Interradials three, in two rows, except at the posterior 



