A MONOGRAPH OF THE EXISTING CRINOIDS 313 



Description. — Hartlaub's redescription of the type specimen from Coritrin station 2 

 is as follows: The centrodorsal is dome-shaped with a bare dorsal pole; there are 

 strong interradial processes, but no interradial ridges. 



The cirri are XVI, all broken off beyond a few basal segments. According to 

 Pourtales they have about 15 long segments. Hartlaub said that the first two segments 

 are very short, those following markedly longer than broad. 



The radials are entirely visible; in the proximal portion of the median line they 

 bear a conspicuous tubercle. They are laterally in close contact, and their lateral 

 edges show several small tubercles or dentations which in many places interdigitate 

 with those on the neighboring radials. Their distal border is gently concave. The 

 IBr! and IBr 2 (axillaries) have a sharp median keel; together they form a synarthrial 

 tubercle which does not appear as a unit, since the two ridges are separated by the 

 articulation. The IBrj are broadly in contact laterally; their lateral borders, like 

 those of the radials, are tubercular or dentate, and their proximal border is slightly 

 convex and bears very small tubercles. The IBr 2 (axillaries) are pentagonal; their 

 proximal and distal edges are bowed outward and are in places slightly tubercular. 

 They are free laterally. The lateral borders are dentate, but lateral contact surfaces 

 are present. There are two IIBr 2 series. In one of these, which is fully developed, 

 the lateral borders of the ossicles are free, but the inner sides of the first two brachials 

 are in close contact; both these brachials have a slight median elevation of the dorsal 

 surface. The other IIBr series is regenerating. It is followed by a IIIBr 2 series. 



There are 13 arms with an estimated length of 35 mm. The first two brachials are 

 short, broader than long, approximately rectangular; their lateral borders are dentate. 

 From the fourth brachial onward the brachials become longer and more squarish; 

 their proximal and distal ends show a sharp process which is visible on the dorsal 

 surface of the arms. In the middle of the arms the brachials become approximately 

 wedge-shaped and longer, and the processes arise on the sides of the arms. All the 

 brachials are smooth. The ends of the arms are broken off. 



In arms arising from a IBr axillary and in those arising from a IIBr axillary the 

 first syzygy is between brachials 3+4; in arms arising from a IIIBr axillary it is between 

 brachials 1 + 2. The second syzygy is from between brachials 15 + 16 to between 

 brachials 17 + 18, and the third is between brachials 21+22 or 22+23. 



P! is about 3 mm. long, longer than any of those following, with about 13 segments 

 of which the basal three or four are broader than long and the second-fourth are mod- 

 erately carinate; from the fifth onward the segments become gradually narrower and 

 longer. P 2 and P 3 are shorter, about 2 mm. long; the two or three lowest segments 

 are broad. In the pinnules following these become more slender and toward the middle 

 of the arm the basal segments no longer differ from those following. These pinnules, 

 about 2 mm. long, have 6 or 7 stout segments of which the first two are short and the 

 terminal are markedly longer than those of the earlier pinnules. Pourtales said that 

 the pinnules in the middle of the arms have 5 segments. 



The ambulacral surface of the arms and pinnules show sacculi and prominent 

 plating. The disk is 3 mm. in diameter. 



A small specimen from Blake station 232 is not half so large as Pourtales' type 

 specimen, the arms being only about 15 mm. long. Some of the cirri are complete. 

 They have 12-14 segments of which the first two are short and the third, fourth, and 



843803—50 21 



