BATOCRIiSflD^. 407 



by a large radial plate at each bifurcation. The orals pushed anteriorly. 

 Respiratory pores arranged in ten pairs, five of them placed between the 

 rays, the five others between their main divisions; they are well defined, 

 and occupy the margin of the ventral disk, a little to one side of the ambu- 

 lacral openings. 



Distribution. — The only known species occurs in the Keokuk group of 

 the Mississippi Valley. 



Remarks. — The genus AlloprosaUoeriniis is most remarkable for the short- 

 ness of the dorsal cup contrasted with the great height of the ventral disk, in 

 which it resembles Agaricocrinus. The form of the arm facets in the two 

 genera is also quite similar, and they probably had the same kind of arms ; 

 but in Agaricocrinus the anus opens out laterally, directly through the disk, 

 while in AUoprosallocrinus it is placed at the end of a tube, and besides, the 

 former having two well defined costals. 



Meek and Worthen's Alioj^'osallocrinus euconus is a Dizygocrinits ; it resem- 

 bles the former somewhat in its form, but it has two costals, the arms are 

 comparatively thin, and become paired in mature specimens. 



Casseday and Lyon's Alhprosallocrinus de2wessus is probably an Aganco- 

 crinus ; the type specimen is too much distorted to admit a correct diagnosis. 



AUoprosallocrinus conicus Cass, and Lton. 

 Plate XLII. Figs. 14a, b, c. 



1860. Casseday and Ltos; Proceed. Amer. Acad, of Arts and Sci., Vol. V,, p. 29. 



1866. SHnjiAED (Subgenus of Actimcriniis) ; Catal. Pateoz. Poss. (Trans. Acad. Sci. St. Louis, Vol, II., 



p. 353). 

 1881. W. and Sp. ; Revision Pateocr., Part II., p. Ill (Proceed. Acad. Nat. Sci. Pliila., p. 288). 



AUoprosallocrinus Gurleiji S. A. Miller; 1891, Adv. Sheets 17tli Rep. Geol Surv. Indiana, 



p. 58, Plate 10, Figs. 1 and 2. 



Calyx pyramidal ; the dorsal cup so flat that it is almost invisible from 

 a side view ; the ventral disk high and distinctly conical. Plates thick and 

 devoid of ornamentation ; those of the dorsal cup very slightly convex ; the 

 plates of the tegmen varying from convex to nodose. 



Ba.sals small, forming an inverted hexagonal basin. Eadials wider than 

 high, the lower portions bending inward, and forming a part of the basal 

 concavity. Costals generally so closely anchylosed that a suture line cannot 

 be traced, both together are pentangular, a little wider than the radials, and 

 wider than long. Distichals 2X2, except in the posterior rays, of which the 

 divisions next to the anal interradius have but one, which is axillary and 



