63 



PLATYCRINUS CONCINNULUS, 11. sp. 



Plate IV, Fig. 16, azygous side; Fig. 17, opposite view; Fig. 



18, summit view. 



Species medium or above medium size. Calyx urn-shaped, 

 rounded below, slightly projecting at the arms so as to give 

 it a subpentagonal outline when seen from above, and about 

 one-fourth wider than high. Surface finely granular. Sutures 

 slightly beveled. Column round. 



Basals form a low, rounded cup, pentagonal at the top, and 

 bear a slight constriction or furrow in the middle part above 

 the end of the column. First radials expand slightly and are 

 a little longer than wide. They are convex toward the facets 

 for the second radials. A facet occupies a little more than 

 one-third the diameter of the plate and is semi-circular in out- 

 line, and notched for the ambulacral canal. The second radials 

 are very short and axillary, giving ten arms to the species. 



The regular interradials are rather large and curve abruptly 

 over on the vault. The azygous interradial stands nearly up- 

 right and forms one side of the base of the proboscis. 



Vault low, neaily flat, and covered with a few convex and 

 subnodose plates. A highly nodose plate covers the junction 

 of the ambulacral canals at the base of each arm. The base 

 of the proboscis is large and subcentral, but the height is un- 

 known. 



The lower part of the calyx of this species resembles P. 

 concinnus, but the vaults are altogether different, and that 

 species has eighteen or twenty arms, and this one has only 

 ten. The constriction around the basal plates will distinguish 

 this species from nearly all the urn-shaped species, and none 

 that have been described have a vault similar to this one. 



Found in the Burlington Group, at Sedalia, Missouri, and 

 now in the collection of F. A. Sampson. 



Family CARYOCRINID.E. 



CARYOCRINUS MILLIGAN.K, 11. Sp. 



Plate V, Fig. 3, azyqous side view; Fig. 4, summit. 

 Species medium to large size, rapidly spreading to the middle 

 of the second range of plates, where it has an hexagonal out- 



