14 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 74 



turbinate, the sides diverging evenly from the infrabasal circlet to 

 the arm bases, with a slight outward flare at about the top of the 

 basals. The tegmen is low. 



The infrabasals form a fairly distinct ring which is, however, not 

 as sharply set off from the remainder of the cup as in the case of 

 V. valens. The lower outer margins of the infrabasals are somewhat 

 produced, forming a low rounded interrupted ridge surrounding the 

 base. The basals are variable in size. The posterior and right pos- 

 terior basals are heptagonal in outline. The r. post. B supports RA 

 on its upper left shoulder. The post. B supports RA on its upper 

 right shoulder and plate x above. The surface of the basals is most 

 elevated near the center of the plate. From this point rounded 

 ridges radiate to the adjacent plates, forming depressed areas along 

 the interbasal sutures as in Y . valens. In addition to these larger 

 ridges there are inconspicuous folds or ridges crossing from the basals 

 to the radials. The radials are somewhat variable in size. At about 

 the upper level of the arm facets the radials bend over and inward, 

 forming a narrow shelf. The arm facets are directed slightly up- 

 ward. The radials are pierced by axial canals, which occupy a me- 

 dian position on the arm facets. To either side of the axial canal is 

 a sharply defined articulating facet. RA is large, resting below on 

 the post, and r. post. BB, abutting laterally on r. post. R and x, and 

 supporting rt above. Anal x is still larger and supports two tube 

 plates above. The tegmen is lov\^ and is somewhat depressed at each 

 interradius except the posterior, giving it a somewhat lobate appear- 

 ance. The plates are comparatively heavy, forming a fairly strong 

 rigid tegmen. With the breaking off of the ventral tube a few of the 

 tegminal plates have been lost. The surface of some of the plates 

 has been slightly weathered, giving three or four of them a somewhat 

 roughened and pitted appearance. It is not possible, therefore, 

 definitely to state whether a madreporite is present or not. The stem 

 as shown by the impression of the proximal columnal on the infra- 

 basals is round and pierced by a fairly large pentalobate axial canal. 

 But one brachial is preserved. This is short, stout, and somewhat 

 constricted in its median portion. It is traversed by an axial canal 

 distinct from the food groove. As shown in its proximal portion, 

 the food groove is covered by a series of highly arched covering 

 plates. 



This species differs from V. valens chiefly in the shape and pro- 

 portions of the dorsal cup. The straight sides of V. tiirbinatus grad- 

 ually diverging from the base to the arm facets give it a habit quite 

 at variance with the relatively low rapidly expanding cup of V. 

 valens. 



Horizon and locality. — The specimen was found in a tray with an 

 assortment of crinoids labeled as coming from Louisville, Ky. As 



I 



