580 BULLETIN 82, UNITED STATES NATIONAL MUSEUM VOLUME 1 



There is no ambulacral groove on the 3 or 4 terminal pinnule segments. 



Young individuals of this species have the borders of the elements of the IBr 

 series and of the lower brachials prominently spinous. 



[NOTES BY A.M.C.] A large specimen of prolixa found with a specimen of Helio- 

 metra glacialis taken by the Diana off Spitzbergen, has quite marked interradial spaces 

 between the proximal cirrus sockets on the centrodorsal (fig. 33,6). The basal diameter 

 of this is 3.9 mm. and the vertical height 3.5 mm. There are only three columns 

 of cirrus sockets in each radial area, which are quite regular as they are not overcrowded 

 apically. 



Some measurements of specimens of Poliometra prolixa in the British Museum 

 were made for me by Mr. M. J. Mann, now of the Fisheries Service, Uganda. The larg- 

 est has the width at the first syzygy 2.6 mm. and the length from the proximal edge 

 of the IBr t to the second syzygy 12.0 mm. Unfortunately the corresponding arm 

 length could not be assessed, all being broken, but there were over LXX cirrus sockets 

 and P 2 was as much as 6.5 mm. long. 



Abnormal specimens. One of the individuals from Triton station 4 has only 

 9 arms; on one of the postradial series the first and second brachials of the two arms 

 are very close together and are followed by a common syzygial pair. 



In a specimen from Inyolf station 116 the right anterior and right posterior radials 

 are very closely united laterally; the right anterior radial bears the usual IBr series; 

 the right posterior radial bears an ossicle about four times as broad as long with a 

 muscular articulation of the "straight" type both proximally and distally, which 

 is fused laterally with the IBr, of the right anterior ; this is probably to be interpreted 

 as an additional radial, for beyond it is the usual IBr series. The ossicles of the two 

 rays are fused laterally as far as the first brachial on the right derivative from the 

 right posterior ray, which is fused with the second brachial of the left derivative from 

 the right anterior ray. 



One of the 12 individuals in a jar in the Bergen Museum containing specimens 

 from Vjringen stations 286, 337, 359, and 362 is 6-rayed, the additional ray being 

 inserted between the left anterior and the left posterior as viewed ventrally. 



Mortensen (1910) has recorded a specimen from East Greenland with a forked 

 pinnule, the ramification occurring after the second joint. 



Parasites and commensals. In 1911 Mortensen described an endoproct, Loxo- 

 somella antedonis, found attached to the cirri of some specimens of P. prolixa taken 

 by the Danmark expedition to northeast Greenland. 



Localities. Grinnell Land [Sladen, 1878]. 



Alert; Discovery Bay, Robeson Channel, Grinnell Land (lat. 81 41' N.); 46 meters; 

 hard bottom [P. H. Carpenter, 1877; Sladen, 1881; A. H. Clark, 1913; Th. Mortensen, 

 1913] (5, B.M.). Type locality. 



Falcon; Inglefield Gulf and Murchison Sound, western Greenland (lat. 7730' N.) 

 [Ohlin, 1895]. 



Sofia station 542; Melville Bay, northwestern Greenland Gat. 7526' N., long. 

 6727' W.); 475 meters; hard clay with stones; July 29, 1883 [Gisle"n, 1923]. 



Ingegerd and Gladan station 17; Baffins Bay, west of Arpik, Greenland (lat. 7232' 

 N., long. 5805' W.); 212 meters; stones; J. Lindahl, July 18, 1871 [GislSn, 1923]. 



Esquimaux; off Cape Raper, western side of Davis Strait (about lat. 70 N.); 

 110 meters; sand and small stones; September 9, 1892 [Rodger, 1893]. 



