BATOCEINIDiE. 513 



Another small species of the type of A. hrevis, but its calyx shorter and of 

 somewhat different form, being about twice as wide as high, and i^yramidal 

 in outline. Dorsal cup sharply pentangular and distinctly flattened at the 

 bottom. When placed on end, it rests upon the costals, the basals and radials 

 forming a shallow, funnel-shaped concavity, and the distichals bending 

 slightly upward. The costals and distichals curve to the sides, so as to 

 form a depression at the interradial spaces, and each plate has a narrow, 

 transverse, angular ridge. The suture lines are distinctly grooved. 



Eadials rapidly spreading ; their upper faces twice as wide as their 

 lower, the upper end thickened, corresponding to the transverse ridges 

 of the brachials. First costals very short, more than twice as wide as 

 long ; the second a little wider and longer in proportion. Distichals almost 

 as short as the free arm plates ; the second considerably wider than the first, 

 and followed by two series of arm plates, of which the two inner series of the 

 ray interlock with the second free plate, i. e. fourth plate from the axillary. 

 Ann facets large, confluent, and those of adjoining rays almost in contact. 

 Arms ten, massive at the bases, quite thin at the extremities; composed of 

 two rows of short parallel joints, with transverse, obscurely angular ridges. 

 First interbrachials large, attenuate at the upper end, their surfaces convex ; 

 the two of the second range long and extremely narrow. The first anal, 

 which is fully as long but not as wide as the radials, is followed by three 

 elongate plates, and these by a large number of irregular pieces, forming 

 a slightly rounded, ridge-like elevation, with a groove at each side. Anus 

 close to the posterior oral, opening out obliquely upward. Ventral disk 

 depressed pyramidal ; the orals and radial dome plates distinctly convex, the 

 interambulacrals almost flat. 



Horizon and Locality. — Same as last. 



Types in the (Worthen) Illinois State collection, and in the University 

 Museum at Ann Arbor, Mich. 



Agaricoerinus gracilis M. and W. 



Plate XLI. Figs. 3a, h, c. 



1861. Meek and Worthen; Proceed. Acad. Nat. Sci. Pliila., p. 135. 

 1881. W. and Sr. ; Revision Pateocr., Part II., p. 112. 



Somewhat smaller than A. hrevis ; the calyx wider than high ; in its 

 ventral aspect decidedly pentangular with concave sides. Dorsal cup de- 



