132 BULLETIN 82, UNITED STATES NATIONAL MUSEUM 



The IBr 2 (axillaries) are very short and triangular. The apposed edges of the elements 

 of the IBr series, and sometimes also of the elements of the IIBr series, are thickened. 



The 2 best preserved specimens have each 16 arms, both having a single IBr 

 series without any IIBr series following. The arms are very slender. On arms 

 arising from IBr axillaries the 2 first brachials, through being flattened dorsally and 

 having produced lateral borders, have the appearance of the elements of IIBr series. 

 But on arms arising from IIBr axillaries the first 2 brachials are not broadened, 

 although they are somewhat more flattened than the succeeding brachials. The 2 

 first syzygial pairs are about as long as broad; then follow 2 oblong brachials which 

 are somewhat shorter than the syzygial pairs, then a wedge-shaped brachial, and 

 then a series of triangular brachials of moderate length which on about the twenty- 

 seventh pass over again into wedge-shaped brachials. The arms are almost entirely 

 smooth, and are rounded dorsally. 



In arms arising from IIBr axillary syzygies occur between brachials 1+2 and 

 3 + 4, then from between brachials 13 + 14 to between brachials 18 + 19 (most com- 

 monly from between brachials 13 + 14 to between brachials 15 + 16), and distally at 

 intervals of 4 or 5, or 3 or 4, muscular articulations. The syzygy between brachials 

 3 + 4 may be absent. 



On arms arising from a IBr axillary the first syzygy is between brachials 3 + 4. 



The character of the pinnules agrees with that of the arms. They are slender, 

 and the 2 basal segments are in no way remarkable for any broadening. 



PI has about 40 segments which after the tenth become very slender; about 12 

 of the distal bear a prominent comb. 



The character of the following pinnules on the same arm side remains the same 

 as far as Pi, which is 5 mm. long with 23 segments, the last 12 with prominent teeth. 

 P 4 becomes very slender and flagellate after the sixth segment. 



From P 5 onward the flagellate character disappears, and the comb is lacking. 

 P 5 and the 2 following pinnules are about 4 mm. long. In these the basal segment is 

 smaller than the second. The distal decrease in the size of the segments in these 

 pinnules is more gradual than is the case in the pinnules preceding. Spinous keels 

 occur only on the third and fourth segments of the pinnules following P 3 , and are not 

 prominent. 



The pinnules in the middle of the arm are about 5 mm. long, slender and flagel- 

 late, with 15 segments, of which those from the sixth onward are elongated. 



The color of all the specimens is white. 



The specimen examined from St. Paul's rocks is large and has 20 arms. The 

 distal dorsal edges of the pinnule segments are very strongly everted and produced so 

 that the dorsal profile of the pinnule is deeply serrate. The longest cirrus stump 

 remaining is 12.5 mm. long and consists of 9 segments, of which the sixth is the longest 

 and is slightly over twice as long as broad; the segments following are slightly shorter; 

 the sixth and following segments have the distal dorsal edge slightly produced. 



Doctor Hartlaub gave a composite description of the many armed specimens of 

 this species which he examined, practically all of which were from the Blake collection. 



He says that the centrodorsal varies in its form from a broad, thick, flat, some- 

 times sharply pentagonal disk with 2 marginal rows of cirrus sockets (specimens from 



