|S BULLETIN 82, UNITED STATES NATIONAL MUSEUM 



cave. All the margins are finely serrulate and the lateral surfaces arc rough and spinu- 

 lose. The synarthrial tuhcrcle is smooth and rounded, low but distinct. The IIBr 

 scries are '-', M'i'.v similar to the IBr series,; hut the lateral spinulose surfaces are much 

 less marked, especially on the axillary, and are nearly wanting on the inner side. The 

 division series and first two brachials have strongly flattened sides. The division 

 series arc in closely appressed contact, but the lower brachials are mucli less so and 

 probably in life hardly touch. 



The 20 arms are about 90 mm. long. The first two brachials are similar to the 

 elements of the IIBr series but are relatively much longer and narrower and have no 

 spinulose lateral areas, though the lateral margins are very serrulate and rough. The 

 third-tenth brachials are quadrilateral, the following brachials becoming triangular, 

 the distolateral angle being more and more prominent. Beyond the middle of the arm 

 the brachials become quadrilateral again and nearly as long as broad. Proximally 

 both proximal and distal margins are everted and rough, but beyond the twelfth to 

 fourteenth brachial only the distal margin is conspicuous; even near the tip of the arm, 

 however, the distal margin is not very flaring and it never overlaps the segment fol- 

 lowing. Beginning at the thirty-fifth brachial, or thereabouts, the distal dorsal surface 

 of each segment is rough with minute spines, and these soon cover the whole median 

 area of the arm; near the arm tip this area is a very narrow band. 



The first syzygy is between brachials 3 + 4. In eleven arms of one specimen, but 

 in only one arm of the holotype, the second syzygy is between brachials 5 + 6, and the 

 third is somewhere in the region between the eighteenth and twenty-seventh brachials. 

 In the other arms the second syzygy is generally not until after the twentieth brachial. 

 The distal intersyzygial interval is at first 6-8 muscular articulations, but near the tip 

 of the arm it decreases to 4 or 5. 



Pi is about 11 mm. long with 25 smooth segments of which the six basal are much 

 broader than long, somewhat axe-head shaped, and much flattened dorsally, and the 

 remainder are longer than broad, or at least as long as broad, the eighth being the 

 longest. Pj is similar but only 10 mm. long with only 22 segments. P 3 is similar, but 

 a little shorter. P t to P, are more prismatic, only 5-6 mm. long, with 12-14 segments 

 which have the distal margins, and a sharp dorsal keel, finely serrulate. The remaining 

 pinnules are similar but becoming much more slender, longer (8-10 mm.), and with 

 more segments (17-18); the sharp serrate dorsal keel is well marked. 



The color in alcohol is yellowish brown ; when dry the shade is much lighter. 



Notes. — In a cotype which Dr. Clark very kindly permitted me to examine the long- 

 est cirrus is •"(> nun. long with 74 segments of which the seventh is a transition segment ; 

 the longest segments are half again as long as broad. The crest of the dorsal cirrus 

 spines is broad, on the average occupying about the median third of the segments in 

 dorsal view. In lateral view the distal (vertical) edge of the spines is finely serrate, 

 most pronouncedly so in the outer third of the cirri. 



The outer (lateral) thirds of the ossicles of the IBr scries and IIBr series appear 

 spongy; there arc a few small spicules on the adjoining edges of the ossicles of the IIBr 

 series. 



The earlier brachials have the borders thickened and rather abruptly everted, 

 ilioiigh not produced. As the brachials become triangular small spines are developed 

 along the distal border which gradually increase in size, especially those in the middle 



