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Se en ee SSS ne SS Se ae —EEE — 
700 THE CRINOIDEA CAMERATA OF NORTH AMERICA. 
'‘Platycrinus peculiaris W. and Sp. (nov. spec.). 
Plate LXVITI, Figs. 7a, 0. 
| Of medium size. Calyx one third higher than wide; the dorsal cup 
ae: : about as wide as high, obconical at the base, cylindrical along the radials ; 
| | the plates rather thin. The ornamentation of the plates cannot be accu- 
H L 4 rately ascertained in the specimens, but the surface shows traces of obscure 
| Pe Bi ridges passing down diagonally from the radial facets to the lower angles of 
im the radials, and from the column up to the angles of the basal cup, which 
suggests that the surface was marked in a similar manner as in P. sculptus, 
but perhaps less distinctly. The sutures slightly grooved. 
Basal cup basin-shaped, its height equal to one-half the length of the 
Ht | radials, gradually expanding upwards, and slightly beveled around the upper 
margins; the column facet small, somewhat projecting, and the interbasal 
suture lines distinct. Radials subquadrangular, nearly as wide as long, the 
median line sometimes a little elevated, the lower faces very slightly convex; 
the lateral faces almost parallel, the sloping upper faces wide and forming 
i= broad interradial notches, of which that at the anal side is deeper than the 
H others.. Facets extremely small, not occupying more than one fourth the 
| width of the plates, and often considerably less. Costals small, as long as 
H | wide, occupying the entire facet. Distichals narrow, almost as long as wide, 
all in sutural contact with adjoining interradial plates, and as such constitut- 
a 7 ing a part of the calyx, although having the form of free arm plates, Ven- 
| ; tral disk hemispheric, slightly bulging at the anal side, studded with numerous 
im 7 | small, nodose pieces, of very nearly equal size. The orals unusually small ; 
the ambulacral pieces on a level with the other disk plates, and of the same 
size; they are very regularly arranged, and branch upon the disk. The 
| interradial plates consist of three rows of three each; those of the first row 
| | are perfectly flat, and interbrachial in position, the others being nodose and 
ania interambulacral; the middle plate of the first row very large, oblong and 
| |  heptagonal, the two at the sides as long, but very much narrower. Anus 
excentric, at the top of a small protuberance. Number of arms unknown. 
ti 7 Horizon and Locality. — Lower Burlington limestone ; Lake Valley, New 
yl Mexico. 
Type in the collection of Wachsmuth and Springer, 
ifm — 
