A MONOGRAPH OF THE EXISTING CRINOIDS 419 



The arm length of these 2 specimens is about 200 mm. Hartlaub remarked that 

 the unusual length of the arms is very remarkable, as Carpenter described the arms 

 as short; he suspected that hi Carpenter's specimens the arms were not preserved for 

 their full length. The distal portion of the arms is exceedingly slender, so that if 

 they are broken their length may easily be underestimated. 



Hartlaub observed that the syzygial nature of the union of the elements of the 

 IBr series is debatable. The articulation described by Carpenter as syzygial Love'n 

 considered as a synarthry, and Hartlaub said that after a careful study of the case he 

 might adopt this latter view. He remarked that the radial sculpture characteristic 

 of all syzygial joint faces is lacking, but instead, as is also the case with the articulation 

 between the first 2 elements of the IIBr series, there are prominent concentric ridges, 

 and in the dorsoventral line a joint axis in the form of an inconspicuous lulcral ridge. 

 Also it is seen on a cross section that the joint face has a prominent epiphysis; that is, 

 a calcareous mass present on all the articular surfaces which lies on that of the ossicle 

 itself, from the substance of which it is distinguished by its denser texture. Also it 

 must be admitted that the appearance of the articulation is not essentially different 

 from that of the comparable articulation in Comanthina schlegelii. 



In discussing the specimen from Jobie, Carpenter said that the characters which 

 he believed to be especially distinctive of the species (typica) are the following: 



The centrodorsal is stellate, with few or no cirrus sockets, and nearly flush with 

 the radials. The elements of the IBr series are united by syzygy, but the articular 

 line is rarely dotted. The rays may divide seven or eight times. The IIBr series 

 are 4 (3 + 4), the subsequent division series being 2 (1 +2). The first 2 brachials are 

 united by syzygy, and the next syzygy is usually somewhere between brachials 9+10 

 and 11 + 12. The distal intersyzygial interval is 3 muscular articulations. 



The pinnules decrease in length to about the sixth brachial, and then increase 

 again, though the following pinnules rarely, if ever, reach the length of the lowest 

 pinnules. The segments of the middle and later pinnules are very spiny. 



The mouth is usually subcentral and radial, but the ambulacral grooves are 

 unequal. The anus is marginal. 



He noted that the specimen from Jobie is an exceedingly fine one, with the disk 

 measuring 20 mm. in diameter and the arms 125 mm. long. It is remarkable for 

 the great length of its lowest pinnules, the first one reaching 16 mm., and also for 

 the great development of spines on the elongated segments of the middle and later 

 pinnules, the edges of which are fringed with strong spines, while a still larger one 

 projects forward and upward on each side near the distal end. 



In Mliller's type specimen from Eidouma, as redescribed by Carpenter, the 

 centrodorsal is a thin pentagonal disk with its angles slightly produced and about 

 15 cirrus sockets on its sloping sides. 



The cirri are all lost. 



Traces of subradial clefts appear between the sides of the centrodorsal and the 

 inner margins of the short radials. 



The IBrj are shorter than the radials, widely hexagonal and only partly united 

 laterally. The IBr 2 (axillaries) are free, pentagonal, barely two and one-half times 

 as long as the IBrj, to which they are united by syzygy. The IBr series are quite 



