320 THE CRINOIDEA CAMERATA OF NORTH AMERICA. 



gate nodeS; radiate from near the middle of the radials and costals to the 

 larger interbrachials^ the latter having generally four such ridges to each 

 side of the plate, arranged parallel. Toward the upper part of the dorsal 

 cup the ridges almost disappear, and the plates are simply tumid. 



Basal disk depressed funnel-shaped ; the outer rim on a level with the 

 radials; perforated by a large^ pentalobate canal with sharp re-entering 

 angles, which extend deeply inward. Radials larger than the costals, their 

 length equal to^the width at the lower end; the truncated upper faces con- 

 cave ; the sloping upper faces much shorter than the sloping lower. First 

 costals subquadrangular, narrower than the radials; upper and lower sides 

 convex. Second costals very httle wider, but considerably longer and pen- 

 tangular. Distichals 1X10; all axillary ; almost as large as the second 

 costals. Palmars much smaller, the two lower ones, w^hich are short and 

 lunate, incorporated into the calyx. Arm openings arranged in groups ; 

 large ; directed obliquely upwards. Primary arms twenty. Interbrachial 

 spaces wide, the plates arranged : 1, 1, 2 ; the first larger than the radials ; 

 the second almost as large as the first costals, subquadrangular ; the two of 

 the third row much smaller. Between the arm openings are three to five 

 minute pieces, which are followed by two large elongate plates in the teg- 

 men, and several additional plates at the anal side. There are four slits to 

 each interradlal space, and the same number to each interdistichal space. 

 Ventral disk low-hemispherical, surmounted by a medium sized almost cen- 

 tral tube ; the course of the ambulacra marked by an elevation, the inter- 

 ambulacral spaces depressed, especially near the outer margin; the plates 

 completely covered with small pustules of even size. Orals and ambulacral 

 plates as usual in the genus. Column round, the joints with slightly waving 

 edges, and rapidly increasing in size downwards; the nodal joints projecting. 



Horizon and Locality. — Hamilton group ; Louisville, Ky. 



Types in the collection of Wachsmuth and Springer, and Victor W. Lyon. 



Remarks. — This species bears some resemblance to " Cacahocriniis " 

 lamellosus Hall ; but differs considerably in the form and size of the basal 

 depression, which in the latter species, according to Hall, is large, sub- 

 circular, and embraces the basals and one third of the radial plates. It also 

 occurs at a different geological horizon. 



