54 BULLETIN 82, UNITED STATES NATIONAL MUSEUM 



bear a median transverse dorsal ridge which appears as a small spine in lateral view. 

 At first the crest of this ridge as viewed from the end of the segments is practically a 

 straight line, but it gradually becomes more and more convex and at the same time 

 narrower so that on the terminal segments it resolves itself into a laterally elongated 

 centrally arched tubercle. The opposing spine is short, but prominent, median, erect, 

 equal in height to about one-fourth the width of the penultimate segment. The 

 terminal claw is slightly shorter than the penultimate segment, stout and rather 

 abruptly curved proximally, becoming slender and nearly straight distally. 



The radials are between two and three times as broad as long. The IBr! are 

 trapezoidal, about twice as broad as long, basally in lateral contact, gradually separat- 

 ing distally. The IBr 2 (axillaries) are broadly pentagonal, about half again as broad 

 as long. 



The 10 arms are about 25 mm. long. The first brachials are wedge-shaped, 

 ulteriorly united for almost their entire length. The second brachials are similar, but 

 proportionately longer. The first syzygial pair (composed of brachials 3+4) is 

 oblong, about as long as broad. The following brachials to the eighth are oblong, 

 about twice as broad as long, then becoming triangular and about as long as broad, 

 and wedge-shaped and longer than broad distally. Synarthrial tubercles are more or 

 less, but never strongly, developed. 



Syzygies occur between brachials 3+4 and 7+8, and distally at intervals of 3-5 

 (usually 4) muscular articulations. 



P! is comparatively long and stout, tapering uniformly from the base to the tip, 

 with 12 segments of which the first is about as long as broad, the second is half again 

 as long as broad, and the third and following are about twice as long as broad, slightly 

 more proximally, slightly less distally. P 2 is similar, but considerably shorter, with 8 

 segments of which the first is somewhat broader than to as broad as long, the second is 

 about half again as long as broad, and the remainder are about twice as long as broad. 

 P 3 is shorter than P 2 with about 12 segments of which the first is not so long as broad, 

 the second-fifth are about as long as broad and rather stout, and the remainder are 

 longer than broad. P 4 is similar, but the third and fourth segments are slightly 

 broader. The following pinnules have the third and fourth segments laterally ex- 

 panded, forming a roof over the gonads; the fifth segment is expanded proximally but 

 tapers distally, and the remaining segments are slender. This swollen and expanded 

 condition of the pinnule segments persists practically unchanged to Pi 6 , at which 

 point the arms of the specimens examined are all broken off. 



The color in alcohol is yellowish white, transversely banded on each segment with 

 purple, rarely entirely yellowish white or entirely purple. 



Notes. The preceding description was drawn up by me from the original 

 specimens which Dr. Hubert Lyman Clark was so very kind as to permit me to study 

 at Cambridge, Mass. 



Dr. Clark's original description is as follows: 



Centro-dorsal small, low hemispherical, nearly concealed by two marginal rows of cirri; these 

 are about sixteen in number, 7-8 mm. long, with fifteeu-eighteen joints besides the claw; basal joints 

 wider than long, but distally they are squarish; each one, beginning with the fourth, has at middle 

 of dorsal side, a transverse ridge, which in side view looks like a spine, that of the terminal joint being 

 distinctly the largest, but even here not nearly equaling thickness of joint; on basal joints dorsal 

 ridge somewhat serrulate, while distal margin of joint projects as a more or less evident second ridge; 



