460 THE CRINOIDEA CAMERATA OF NORTH AMERICA. 



specimen of Dorycrinus cornic/ents, figured in the Iowa Report, is somewhat 

 misleading by having the arm-bearing plates broken. The calyx therein 

 appears narrower than it naturally is, and gives no idea of the deep sinuses 

 between the arm bases. 



Dorycrinus qulnquelobus (Hall). 

 Plate XLIL Figs. 7, 8, 9. 



1859. Actimcrbms quinquelobua — Hall ; Sappl, Geol. Rep. Iowa, p. 15, and N. Y. State Mus. Nat. Hist., 



Plate ZA, Figs. 18, 19, and 20. 

 1873. Dorycritius quinquelobiis — Meek andWoRTHEN; Geol. Rep. Illinois, Vol. V., p. 380. 

 1881. Syn. of Dori/criims coniigeriis Hall — W. and Sp. ; Revision Palteocr., Part II., p. 179 (Proceed. 



Acad. Nat. Sci. Phila., p. 353). 



A little larger than the preceding .«pecies and more robust; the calyx 

 somewhat higher, broader at the base; the sides less spreading and con- 

 vex ; basals produced downward instead of outward ; costals comparatively 

 larger ; the plates, as a rule, more convex, and the suture lines more dis- 

 tinct. Dorsal cup pentalobate, as high as the ventral di.sk, consti'icted at 

 the basi-radial sutures; the spaces between the rays abruptly, depressed, 

 and forming deep and broad notches within the arm regions. Surface of 

 plates smooth. 



Basals large, broad, the margins of the plates overhanging the top 

 of the column, and forming at the bottom a concavity, which is wider 

 than the column. Radials once and a half as wide as long, the upper face 

 the widest. First costals unusually large, almost two thirds the size of the 

 radials, quadrangular ; sides and upper faces convex. Second costals penta- 

 gonal, hexagonal, or heptagonal, considerably longer than the first, the upper 

 sloping faces rather deeply excavated for the reception of the distichals. 

 The posterior rays, and also the anterior one, have but one distichal in 

 both divisions, which is short and axillary; its upper faces, like those of 

 the costal axillaries, are excavated, supporting a single palmar, which is 

 remarkable for its great length, being fully twice as long as wide. The 

 antero-lateral rays in which there are no palmars have two distichals, of 

 which the first is very short, the second as long as the palmars of the other 

 rays. The great length of the arm-bearing plates is one of the best char- 

 acters of this species ; they bend abruptly outward, are rounded on the 

 back, and are separated from each other by deep notches. Arm openings 

 arranged in groups of four, two, and four ; directed slightly upward. 



