A MONOGRAPH OF THE EXISTING CRINOIDS 449 



laterally. The IBr 2 (axillaries) are more or less pentagonal; both the IBrj and IBr, 

 are rather short. The IIBr series are 2. IIIBr series are absent or of sporadic 

 development. The ossicles from the IBrj to the first and occasionally also the second 

 brachials bear on the outer side a rather strong lateral extension. On the axillaries 

 this has an oblique position and pertains partly to the proximal border of the ossicle. 

 The arms are about 20 in number and are about 85 mm. long. One of the two speci- 

 mens from Mortlock Island has 17 arms. The arms are smooth. The first brachials 

 are almost rhombic. The second are of the same size as the first. Their proximal 

 edge is bowed outward posteriorly, and on arms arising from a IBr axillary their 

 lateral borders are thickened. The first syzygial pair (composed of brachials 3+4) 

 is somewhat broader than long. The three following brachials are approximately 

 discoidal. From the ninth onward the brachials are almost triangular, soon becoming 

 shorter and more bluntly wedge-shaped; at the end of the arms they are more squarish. 

 The first syzygy is between brachials 3+4, the second is at about brachials 13 + 14, 

 and the distal intersyzygial interval is three to five muscular articulations. On arms 

 arising from a IBr axillary the second syzygy is between brachials 9 + 10. 



Pi is delicate, slender, and flexible, with 15, or at the highest 20, segments most of 

 which are longer than broad. It is longer than P a but usually only half as long as 

 P 2 . P 2 and P b are much thicker and are stiffened throughout, straight and spinelike. 

 They are 9-10 mm. long and are composed of 12 greatly elongated segments, of which 

 the fourth and fifth are markedly the longest. P 3 and P c are not half so long as P 2 

 and P b ; they are flexible and of the same character as the pinnules succeeding. Of 

 these last the first three or four pairs are of approximately the same length, those 

 following becoming longer and reaching 8 mm. The disk is 11 mm. in diameter and 

 is strongly incised. Sacculi are abundant and closely set on the pinnules. The 

 color in alcohol is light brown, sometimes with broad dark-brown bands on the arms. 

 The disk is dark brown. The specimen from Ebon, Marshall Islands, in the Museum 

 of Comparative Zoology, was described as a new species, Himerometra heliaster, in 

 the following terms: The centrodorsal is low hemispherical or thick discoidal, with the 

 cirrus sockets in two or three more or less irregular marginal rows. The cirri are 

 XXX-XXXV, 17-23, from 20 to 23 mm. long. The segments are mostly rather 

 longer than broad, and the distal are without dorsal spines. The opposing spine is 

 well developed. The terminal claw is short and curved. The radials are concealed. 

 The IBn are oblong, short, about four times as broad as long. The IBr 2 (axillaries) 

 are pentagonal and somewhat broader than long. The IBr series are well rounded 

 dorsally and are widely free laterally, and they bear a slight synarthrial tubercle. 

 The IIBr and IIIBr series are 2; the axillaries resemble the IBr axillaries, but the 

 preceding ossicle is proportionately somewhat longer than the IBr^ The arms are 

 25-30 in number and 125 mm. long. The first five or six brachials are oblong and 

 slightly tubercular, those succeeding are wedge-shaped, the seventh or eighth is 

 nearly triangular, much broader than long, and those following become graduall} 7 

 less and less obliquely wedge-shaped, and practically oblong at the tips of the arms. 

 Syzygies occur between brachials 3+4, again from between brachials 17+18 to 

 between brachials 21+22, and distally at intervals of from 2 to 12 (usually 6 or 7) 

 muscular articulations. 



