202 BULLETIN 82, UNITED STATES NATIONAL MUSEUM VOLUME 1 



axillary and syzygial, its epizygal bearing two subequal arms of some 60 segments each. 

 The second segment of the left-hand one, which continues the primary arm, has a bifid 

 pinnule with its basal segments enlarged, and the following pinnules alternate regularly 

 on opposite sides. The arm borne on the right or inner facet of the axillary 32nd 

 brachial has no pinnule until its third segment, which is not syzygial, though the fourth 

 is; but in other respects the arm is normal. The second facet of the axillary 30th 

 brachial bears a normal arm of about 60 segments with a pinnule on the second and a 

 syzygy in the third. Thus the axillary 29th brachial of the primary arm 62 gives rise 

 to four well developed arms, two of which bear bifid or trifid armlets in addition to the 

 larger bifid armlet on the 28th brachial. The primary arm ei does not seem to have 

 undergone any regeneration and is normal to the 40th brachial. The 41st is syzygial, 

 and the appendage of its epizygal is a short armlet of three segments, the second and 

 third of which bear pinnules laterally, while its main axis is also continued on in the 

 form of a pinnule. The 42nd brachial has a similar armlet, with but one lateral pinnule. 

 The 43rd is axillary, without a syzygy, its inner branch being a normal arm with some 

 40 segments remaining, the second and fourth of which have pinnules, though the third 

 has not. The 44th segment of the primary arm seems to be syzygial, and its epizygal, 

 though not regularly axillary, supports an arm which has the first pinnule, as usual, 

 on the second segment, but on the inner instead of on the outer side. The next five 

 segments are all enlarged and bear bifid or trifid armlets, while the remainder of the 

 arm is normal, with regularly alternating pinnules. 



With a forked oral pinnule: W. B. Carpenter (1866) mentions a specimen with one 

 of the PI bifurcating on the second segment so that two full sized pinnules take the 

 place of the ordinary single pinnule. 



With an abnormal disk: P. H. Carpenter (1884) records a specimen from Milford 

 in which only four of the ambulacral grooves reach the mouth, the fifth (the left antero- 

 lateral) having a second mouth all to itself. 



With an ovary within the visceral mass: P. H. Carpenter (1884) describes a speci- 

 men in which he found a small but well developed ovary occupying the position of the 

 genital plexus beneath the left posterior ambulacrum of the disk. The first traces of 

 it appear in the sections which pass through the hinder part of the spongy organ, and 

 it extends outward to the point where the primary radial groove divides into the two 

 which proceed to the arms. It contains the nuclei of half a dozen ova in various stages 

 of development, some with a germinal spot and some without. 



Localities. Shetland (Zetland) Islands. Shetland [Forbes, 1851; Norman, 1862, 

 1865] (6, U.S.N.M., 8793). Same, shallow water [A. H. Clark, 1913] (about 6, B.M.). 

 Same, 13 meters [Forbes, 1851]. Same, 18 meters [Forbes, 1841]. Balta Sound [A. H. 

 Clark, 1913] (19, B.M.). St. Magnus Bay, off Papa Stour (island); 46 meters; broken 

 barnacles and serpulae; strong tideway [Forbes, 1851]. Bressay Sound; 9-13 meters 

 [von Graff, 1884]. Same, about 18 meters; rocky; June 1875 [Mason, 1876]. Ling 

 Bank; 90 meters; sand and stones [Forbes, 1851]. 



Orkney Islands. Orkneys [Busch, 1851; Dalyell, 1851; Parkes, 1891]. Same, 

 14-28 meters [Forbes, 1851]. Kirkwall Bay [Busch, 1849; Wyville Thomson, 1864; 

 Norman, 1865]. Same, 11-15 meters [Busch, 1851]. 



Plateau northnorthwest of North Rona (lat. 5912' N., long. 557' W.); 97 meters; 

 rough ground; H.M.S. Knight Errant, 1880 [P. H. Carpenter, 1884, 1888]. 



North Atlantic Ocean [P. H. Carpenter, 1884; A. H. Clark, 1911] (1, L.M.). North- 



