256 BULLETIN 82, UNITED STATES NATIONAL MUSEUM 



P 3 is about 15 mm. long, and P 4 is 16 or 17 mm. long, resembling P 2 . PS is similar, 13 

 mm. long. P a is similar and of the same length. P 7 and the following pinnules are 12 

 mm. long with the segments on the proximal two-thirds slightly expanded laterally. 

 In the course of the following four or five the pinnules decrease in length to 8 mm., while 

 the expansion of the segments becomes more pronounced, beginning on the second, 

 reaching a maximum on the fourth or fifth, then gradually dying away distally. The 

 distal pinnules are 10 mm. long and stout, as in the other species of the genus. 



Side- and covering-plates are well developed. The disk is completely covered by 

 a pavement of small plates. 



Notes. The specimen from Albatross station 5325 was described as a new species 

 under the name Pachylometra luna in the following terms. 



The centrodorsal is as in P. investigatoris, but is proportionately shorter; the cirrus 

 sockets are arranged in 10 columns of 2 or 3 each. 



The division series and arm bases are essentially as in P. investigatoris, but the 

 basal rays are much larger, rhombic, entirely concealing the radials in the interradial 

 angles of the calyx. The division series and arm bases make a slightly greater angle 

 with the dorsoventral axis than in G. investigatoris, though in general the shape and 

 proportions are the same. The division series are more convex dorsally than are those 

 of G. investigatoris, and the center of each in the median dorsal line rises into a broadly 

 rounded tubercle instead of being obscurely carinate as in G. investigatoris. Similarly, 

 indistinct broad tubercles occur on the oblong proximal brachials. The interradial 

 angles are slightly more deeply excavated than are those of G. investigatoris. All the 

 IIBr series are 4(3 + 4) and all the IIIBr series are 2(1+2), all but a single one of the 

 latter being developed internally. 



The 29 arms of the type specimen are 150 mm. long. 



One of the specimens from off Zamboanga has 27 arms 180 mm. long. All the 

 IIBr series are 4(3+4) and there are seven IIIBr 2 series, all internally developed. 

 The proximal profile of the division series and arm bases is broadly rounded. The 

 centrodorsal is large, conical, with the cirrus sockets in 10 columns of 4 each. The two 

 columns in each radial area are closely crowded against those of the adjacent radial 

 areas and are separated in the midradial line by a bare area about the width of a cirrus 

 socket or somewhat less. The cirri are XL, 24-27, from 45 to 50 mm. long. The first 

 segment is very short, the third is about twice as broad as long, the sixth is about as 

 long as broad, and the eighth and following are about one-third again as long as broad. 

 Toward the end of the cirri the segments often become slightly shorter, but the last 

 two are longer again, the penultimate usually half again as long as broad. The outer 

 segments are more or less sharply carinate dorsally. This specimen is larger than the 

 largest in the type series of helius from Siboga station 254 but does not appear to differ 

 from them in any essential particular. 



Another specimen from off Zamboanga has 29 arms 170 mm. long; there are ten 

 IIBr 4(3 + 4) series and nine IIIBr 2 series, the latter all internally developed. The 

 cirri are XXX, 23-24, up to 40 mm. long; the outer cirrus segments are more or less 

 carinate. 



A third specimen from off Zamboanga has 30 arms, ten IIIBr 2 series being present, 

 all internally developed. 



