90 BULLETIN 82, UNITED STATES NATIONAL MUSEUM 



In the larger specimen collected by Dr. H. Merton west of Ngaiguli, Aru Islands, 

 there are almost 90 arms with an estimated length of about 100 mm. The centro- 

 dorsal is thick and hemispherical in form. The cirrus sockets are arranged in 2 or 3 

 rows. The cirri are XLII, about 50, and reach 45 mm. in length. The 20 distal 

 cirrus segments bear prominent dorsal spines. All the division series without excep- 

 tion are 4(3+4). P t is somewhat longer than P 2 , reaching 25 mm. in length; the 

 proximal portion to the fifth segment tapers slightly, but from that point onward the 

 pinnule becomes more rapidly flagellate. P! and P 2 are composed of 53-56 segments. 

 P 3 and P 4 resemble the first two pinnules hi structure but decrease in length and in 

 the number of their component segments. The color in alcohol is whitish; on the 

 dorsal side of the arms there is a broad deep-violet stripe that runs to the centrodorsal ; 

 this is narrowly interrupted on almost every axillary. 



The smaller specimen has 54 arms. As in the preceding, the division series are 

 without exception 4(3+4). The centrodorsal is as in the other, and bears 45 cirrus 

 sockets. The cirri are composed of about 50 segments. Pj and P 2 are up to 18 mm. 

 long. As in the case of the other specimen, the disk is lacking. 



Dr. Merton's other specimens from the Aru Islands were considered by Reichens- 

 perger to represent a new species that he described under the name of Zygometra 

 mertoni in the following terms: The centrodorsal is discoidal with a relatively large, 

 quite flat dorsal pole about 3 mm. hi diameter. The dorsal pole sometimes shows 

 small rudiments of cirrus sockets. The cirri are arranged in one closely crowded 

 marginal row, and there is rarely the beginnings of a second row. The normally 

 developed cirri are XVI-XVIII, 21-23, from 10 mm. to 12 mm. long. The first and 

 second segments are twice as broad as long, the third is slightly longer than the 

 second, and the fourth is about as long as broad. The fifth-ninth segments are 

 markedly longer than broad, the seventh being relatively the longest. From the tenth 

 onward the segments slowly become more squarish. The sixteenth-nineteenth seg- 

 ments are somewhat broader than long, but the penultimate is again as long as broad. 

 From the eighth onward the segments bear a prominent dorsal spine. The opposing 

 spine is stout and reaches about two-thirds the width of the penultimate segment in 

 length. The terminal claw is strong and strongly curved. The middle cirrus seg- 

 ments have somewhat flaring distal ends. 



The radials are rarely visible in the mterradial angles. The IBri are very short, 

 about six times as broad as long, sometimes partially concealed by the centrodorsal. 

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

 series are united by pseudosyzygy. The IIBr series, which are present in most of the 

 specimens, are strikingly Irregular, being sometimes 2 and sometimes 4 (3+4). In 

 one example two of the IIBr series are 2, and three are 4 (3+4). A specimen with 13 

 arms has 2 IIBr 4 (3+4) series, and one IIBr series 5 (3+4) in which the syzygial pair 

 is regularly formed and is followed by a fif th ossicle as the true axillary. In a IIBr 4 

 (3+4) series the third ossicle (hypozygal) is very short, half the length of the second, 

 and the axillary is scarcely longer, almost triangular. The 11-16 arms are 45 mm. 

 long. The first and second brachials are similar, moderately thick, and almost dis- 

 coidal. The first syzygial pair (composed of brachials 3+4) is somewhat longer than 

 the second brachial. The following five or six brachials are approximately oblong, 

 three times as broad as long. Up to this point the ossicles of the division series and 



