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694 THE CRINOIDEA CAMERATA OF NORTH AMERICA. 
Remarks. — This species is apparently a descendant of P. sculptus ; its 
arms, however, are distinct enough for specific separation. It approaches 
Eucladocrinus in the bifurcation of the arms, but the brachials from which 
the arms are given off to one half the length of the free rays are not formed 
into rigid tubes, but retain the character of arm plates. 
Platycrinus Saffordi Hat. 
Plate LXVITI. Figs. 1, 2, 3. 
1858. Hat; Geol. Rep. Iowa, Vol. I., Part II., p. 635, Plate 18, Figs. 5 and 6. 
1881. W.and Sp.; Revision, Part II., p. 74 (Proceed. Acad. Nat. Sci. Phila., p. 248). 
A large species. Calyx oblong, unusually large in proportion to the 
arms. Dorsal cup urn-shaped, the bottom broadly truncated, the sides 
eradually spreading to the basi-radial suture, and almost cylindrical along 
the radials. Ornamentation of the plates as in the two preceding species, 
but generally somewhat coarser upon the basals, while less distinct at the 
upper portions of the radials. 
Basal cup large and very deep, its height almost equal to three fourths 
the length of the radials; the bottom broadly truncated, almost flat; the 
lower edge sharp, with an undulated outline. Radials subquadrangular, 
and in large specimens nearly once and a half as long as wide; the mid- 
dle portions a little elevated, especially toward the facets, the upper angles 
slightly inflected, leaving a shallow angular depression at the suture line; 
the sides of the plates parallel. Facets small, restricted to the extreme 
upper end of the plates, and occupying but one third of their width. Dis- 
tichals and the plates of the higher orders to the uppermost axillary moder- 
ately long, the first plate of each order narrower than the second, and 
all free from the costals up. Arms short and of moderate size, given off 
alternately ; biserial from the second plate succeeding the axillaries; there 
are from four to six arms in each subdivision, or as many as twelve to 
the ray. 
Ventral disk depressed hemispherical, the plates more or less convex, 
covered with numerous small pustules, and each one crowned with two or 
three conspicuous nodes. Orals very little larger than the adjoining pieces; 
the ambulacral plates on the same plane with the interambulacrals. The 
latter are arranged: 38, 2, 1; the middle one of the first row large and hex- 
angular, that of the anal side a little wider. Anus excentric and directed 
