206 BULLETIN 82, UNITED STATES NATIONAL MUSEUM 



following slowly increasing in length and becoming terminally about as long as broad. 

 The third and following segments have slightly produced distal dorsal edges which on 

 the segments succeeding gradually become narrower and move to a more central posi- 

 tion, on the last five or six preceding the penultimate becoming a very small sharp 

 median spine. The opposing spine is prominent, sharp, slender, subterminal, much 

 larger than the spines on the preceding segments, directed obliquely forward, and in 

 height equal to one-half the width of the penultimate segment. 



The radials are short, about two and one-half tunes as broad as long. The 

 IBr, are oblong, rather more than twice as broad as long. The IBr 2 are pentagonal, 

 broader than long, with the distal edges slightly thickened. 



The 10 arms are from 35 to 40 mm. long and resemble those of D. informis, 

 though the brachials are slightly longer. 



PX is 3.5 mm. long with 11 or 12 segments of which the first is short, the second is 

 about as long as broad, and those following slowly increase in length, becoming three 

 times as long as broad terminally. The pinnule is comparatively stout and resembles 

 P 2 , though, in direct proportion to its lesser length, it is smaller. P 2 is 4.5 mm. long 

 with 13 segments of which the first is short, the second is about as long as broad, and 

 those following gradually increase in length, becoming twice as long as broad distally. 

 The third and following segments have slightly projecting and finely spinous distal 

 edges, especially along the thin ventral distal border. P 3 is 3 mm. long, much smaller 

 and weaker and much less stiff than P 1( with 10 segments. The pinnules following are 

 similar, slowly becoming longer and more slender, and the component segments slowly 

 increasing in length. The distal pinnules are very slender, 5 mm. long. 



The color in alcohol is light pinkish, narrowly and sparsely banded with deep 

 purple, or entirely deep purple. 



The preceding description is based upon the three original specimens from 

 Bagamoyo. 



Notes. The specimen from Mauritius was originally described as the represent- 

 tative of a new species, Decametra mobiusi, in the following terms: The centrodorsal 

 is small and thin discoidal. The cirrus sockets are arranged in a single somewhat 

 irregular marginal row. The cirri are XIV, 14-16, 7 mm. long. The first segment is 

 short and those following gradually increase in length to the sixth which, with those 

 succeeding, is about as long as broad. On the fourth segment a slight projection of the 

 distal dorsal edge begins to appear. This moves progressively anteriorly, on the ninth 

 and following becoming a low, short transverse ridge appearing as a small spine in 

 lateral view, and on the last two or three segments a small median spine. The 

 opposing spine is median in position, slender and sharp, much longer than the processes 

 on the segments preceding, in height equal to about half the width of the penultimate 

 segment. The terminal claw is longer than the penultimate segment and is stout and 

 comparatively slightly curved basally, but becomes more slender and more strongly 

 curved in the distal half. The radials project slightly beyond the rim of the centro- 

 dorsal; their anterolateral angles are widely separated. The IB^ are oblong, about 

 two and one-half times as broad as long. The IBr 2 (axillaries) are broadly pentagonal, 

 about twice as broad as long. The 10 arms are 50 mm. long and resemble those of 

 D. studeri. PI is 4.5 mm. long, slender, evenly tapering, and becoming flagellate 

 distally. It is composed of about 13 segments of which the first is short, the second 



