HEXACEINIDJi;. 759 



Dichocrinus oblongus W. and Sp. (hot. spec). 

 Plcde LXXVII. Fig. 9. 



In the style of ornamentation resembling D. striatus, from which it differs 

 essentially in its very elongate calyx, and in the projoortions of the plates. 

 Calyx almost twice as high as wide, obconical, not contracted at the upper 

 end; the sides convex. Surface covered by six sets of from five to six rather 

 prominent, longitudinal ridges, which in gentle curves pass from the facets 

 of the radials and top of the anal plate to the foot of the basals. These 

 ridges do not cover the entii-e surface of the calyx, but leave upon the lateral 

 margins of adjoining radials a trigonal space, divided by the interradial 

 suture, and covered by obscure, longitudinal ridges, which rest obliquely 

 against the other ridges. 



Basal cup conical, almost as high as the radials, and nearly as high as 

 wide ; slightly truncated at the bottom ; the upper face but little excavated. 

 Eadials once and a half as long as the width of the lower end, a little wider 

 above than below, the lower face almost straight; facets narrow, a little 

 concave, and slightly protruding outward. Structure of arms and ventral 

 disk not known. 



Horizon and Localiiij. — Warsaw limestone, near Bloomington, Ind. 



Type in the collection of Wachsmnth and Springer. 



Dichocrinus liratus Hah. 

 Plate LXXVII. Figs. 3a, b, and Plate LXXVL Fig. 8. 



1860. Hall ; Prelim. Descr. of New Palseoz. Crin., p. 5. 



1861. Hall ; Bost. Joiirn. Nat. Hist., Vol. TIL, p. 290. 



1872. Hall ; N. Y. State Miis. Nat. Hist. (Bull. 1.), Plate 9,1, Kgs. 7, 8. 

 1881. W. and Sp. ; Revision Palieocr., Part II., p. 84. 



Of the type of D. pohjdactylus and D. lachri/mosus, differing from the 

 former in having four or five instead of six to eight arms to the ray, and 

 showing a tendency toward the rhombic sculpturing of D. striatus. Calyx 

 abruptly spreading to the basi-radial suture, and more moderately from 

 there to the arm bases, at which the width is about equal to the length. 

 Surface marked by a few strong radiating ridges, somewhat tending to form 

 triangles or rhombs, modified by transverse lines ; composed of small, closely 



