62 



PLATYCRINUS SUBSCITULUS, n. Sp. 



Plate IV, Fig. J?, ba.saZ view; Eig. 13, summit vietc; Eig 14, 

 azygous side; Fig. I'>, opposite side. 



Species medium or rather below medium size, calyx and 

 vault subcqual, in capacity, and it belon<j:s to the discoid 

 forms. C-'alyx discoid, subpcntaj^oual. about tlirce times as 

 wide as hiji'li. Surface without ornamenlalion, s^ranular, sutures 

 beveled. 



Basals form a pentagonal disc with a concave depression 

 toward the central part, where the column attached. The 

 beveled suture surrounding the disc will allow the (-alyx to 

 rest on the rim of the disc sui'rounding the concave depres- 

 sion. First radials an; directed ujnvard at an angle of about 

 forty-tive degrees and are convex toward the facet for the 

 second radials, which is concave and occupies a little more 

 than one-third of the diameter of the plates, and is a little 

 more than half a circle. The second radials are short, con- 

 stricted, directed horizontally and axillary. 



The interradial areas are depressed so as to leave the form 

 pentagonal when seen from above. The interradials are elon- 

 gated, aiul instead of rising perpendicularly from the calyx 

 are inclined inward so as to contract the vault in the inter- 

 radial areas. 



Vault elevated over the ambulacra] canals and depressed in 

 the ambulacral areas so as to leave only a slight convexity 

 centrally. The plates of the vault are subspinous. A large 

 plate is situated sub;;entrally on the azygous side and sur- 

 I'oundc 1 with seven i)lates, six of which arc subspinous. The 

 azygous orifice is situated between the ambulacral opcuiings, 

 and the lirst azygous plate is shoi'tcr and smaller than the 

 first regiilui- iiit(u-i"idials. Th<; orifice is surrounded by eight 

 plattis. 



This species is distinguished by its general form, freedom 

 from surface ornanis'iit ition of the calyx, quinquelobatn asjioct 

 as seen from aboNc, ])rojecting second radials, and the liniitcd 

 number of plates on the vault. 



Found in the Burlington (iroup, at S.'dalia, Missoui-i, and 

 now in the collection of F. A. Sampson. 



