A MONOGRAPH OF THE EXISTING CRINOIDS 85 



as broad as long. The distal edge of the transition segment is rather strongly produced 

 dorsally. On the following segments this production of the distal dorsal edge takes the 

 form of a rather high transverse ridge with the crest flattened and dentate. Distally 

 this ridge gradually narrows and on the last six segments before the penultimate it is 

 transformed into a low submedian dorsal tubercle. The opposing spine is small, conical, 

 with the apex median or subterminal in position. The terminal claw is about as long 

 as the penultimate segment or slightly longer, rather slender, and gently and evenly 

 curved. The cirri increase slightly in width and thickness to the fourth or fifth segment, 

 then decrease to the end of the transition segment, after which point they remain 

 uniform. 



The ends of the basal rays are visible as prominent and rather large rounded trian- 

 gular tubercles in the angles of the calyx. 



The radials are wholly concealed. The IBrj are chevron shaped, very narrow, with 

 parallel sides, and are in close apposition. In the median line they bear a prominent 

 sharp keel or an elongate tubercle extending the entire length of the dorsal surface. 

 The lateral portions of the distal border may be unmodified, or they maj 7 be extended 

 distally over the proximal portion of the axillaries in the form of a thin broadly scalloped 

 flange. The IBr 2 (axillaries) are broadly rhombic, twice as broad as long; the lateral 

 angles are only very slightly truncated. The dorsal surface may rise to a broad rounded 

 prominence in the center with its maximum height in the proximal half, or the proximal 

 third of the median line may be occupied by a broad longitudinally elongate tubercle 

 or a sharp median keel. The IIBr series are 2, resembling the IBr series, rather narrowly 

 convex hi the median line, but without central tubercles or keels. 



The 20 arms were probably about 90 mm. long. They are very narrow at the base, 

 increasing in width to about the fourteenth brachial and thence gradually tapering 

 distally. The first brachial varies from three times as broad as long in the median line 

 to only half again as broad as long. In the latter case it is wedge-shaped, longer ex- 

 teriorly than interiorly; in the former the proximal and distal borders are parallel as far 

 as the middorsal line, where the distal border turns anteriorly and runs diagonally 

 outward to the outer distal angle. When very short the first brachials have a prominent 

 elongate tubercle occupying the entire length of the median line, but usually the dorsal 

 surface is evenly convex and swollen so that the profile is strongly convex. The inner 

 distal angles are more or less cut away, as are the inner proximal angles of the second 

 brachials, so that conspicuous rhombic water pores are formed. The second brachials 

 are from two to three tunes as broad as long, in shape approximately oblong. Their 

 distal edges are slightly prominent. The first syzygial pair (composed of brachials 3 + 4) 

 is very slightly longer exteriorly than interiorly, usually about half again as broad as 

 long. The hypozygal (third brachial) is oblong, with the distal border raised above the 

 articular line; the epizygal (fourth brachial) is wedge-shaped, longer exteriorly than 

 interiorly, with the distal border prominent. The following eight brachials are wedge- 

 shaped, from three to four tunes as broad as long in the median line, with the longer 

 side about half again as long as the shorter. Their distal edges are usually raised 

 considerably above the bases of the brachials following, giving the profile of this portion 

 of the arm a serrate appearance; they are also usually somewhat thickened and very 

 finely dentate. The succeeding brachials become triangular, slightly broader than long, 



