A MONOGRAPH OF THE EXISTING CRINOIDS 349 



The radials are moderate in length and resemble those of Neometra multicolor 

 except that they are not produced interradially. Their dorsal surface is marked by a 

 series of semicircular pits or gouges which serve to accommodate the proximal por- 

 tion of the cirrus bases. The cirrus sockets all lie partly on the centrodorsal and 

 partly on the radials. The central canals of the cirri, however, always pierce the 

 centrodorsal, though they may be only very slightly below the rim. The elements of 

 the IBr series are united by an exceedingly close synarthry that appears like a syzygy 

 in external view. The IB^ are oblong, from two and one-half to three times as broad 

 as long. The IBr 2 (axillaries) are broadly pentagonal, twice as broad as long. The 

 elements of the IBr series are broad, in close lateral apposition, and slightly flattened 

 laterally just as in Ptilometra australis, and as in that species the ossicles are very 

 thin dorsoventrally. The IBrj have a sharp tubercle in the middle near the proximal 

 border, and another smaller one in the middle of the distal margin. The IBr 2 has a 

 tubercle in the middle of each of the two anterior edges. The IIBr series are 4(3+4), 

 the axillaries and preceding segments of the IIBr series resembling the corresponding 

 ossicles of the IBr series. The IIBri and the first brachials have each a median tubercle 

 on the anterior border; the IIBr 2 has two tubercles on its proximal border. 



The 17 arms are 60 mm. long, the brachials in general resembling those of Pectino- 

 metra magnified. As in that species, there is a rather sharp overlap, especially at the 

 distolateral angles. The arms do not become laterally flattened or carinate distally. 



Pi is about 7 mm. long, small and weak, flexible, and rather strongly prismatic, at 

 first moderately stout but tapering rapidly after the basal third and becoming exceed- 

 ingly slender and flagellate in the outer half. It is composed of IS segments which 

 proximally are broader than long, becoming slightly longer than broad distally. The 

 first segment is about twice as broad as the second, though in comparison with the 

 conditions in the other species of the family it does not seem to be especially enlarged. 

 The second segment is also enlarged, but very slightly. It bears a small dorsal cari- 

 nate process, as does also the third, which is not enlarged. Pa is stiff and spinelike, 

 8 mm. long with 1 segments of which the first is short, the second is about as long as 

 broad, and the remainder are much elongated with slightly spinous distal ends. Pa 

 and P are equal, slightly longer than P 2 but similar to it, with 12 segments. The first 

 segment of P 2 and sometimes also of P 3 has a slight rounded dorsal carination, but is 

 not otherwise modified. P 6 is about as long as P 2 , but is more slender distally and less 

 spinous. The following pinnules are slightly shorter than P s with 11 segments which 

 have slightly prominent distal ends. The distal pinnules are 9 mm. long. All the 

 pinnules are strongly prismatic. 



The side- and covering-plates along the pinnule ambulacra are highly developed. 

 Sacculi are abundant. 



The disk is lacking. The ventral view of the radial pentagon shows a very broad 

 and shallow central cavity with a small central plug. The radial faces are broad lat- 

 erally, but very narrow dorsoventrally, just as in Neometra multicolor. 



Description of the type specimen of O. pericalles. The centrodorsal is 6 mm. in 

 diameter, slightly convex and smooth. There are 17 cirrus sockets the ventral por- 

 tions of which extend well on to the radials. 



The radials are in contact laterally. The IBr series are clearly separated from 

 their neighbors, and the 2 elements of this series are united by syzygy. The IBri are 



