OPHIUHANS OF UNITED STATES NATIONAL MUSEUM. 37 



OPHIOMISIDIUM PCLCHELLUM (WyvUle Thomson). 



Ophiotnusium pulchellum Wyville Thomson, The Voyage of the Challenger, vol. 2, 1877, 



p. 67, figs. 18-19. 

 Opkiomusium pulchellum Lyman ^78), p. 118, pi. 5, figs. 144-145. 

 Ophiomu.mnn pulchellum Lyman (82), p. 96, pi. 3, figs. 1-3. 

 Ophiomusium pulchellum Luowia (00), p. 2. 

 Ophiomumim pulchellum Koehler (07), p. 266. 



Albatross station 2625. Oct. 21, 1885. Lat. 32° 35' N.; long. 77° 30' W.; 

 247 fathoms; gy. s. bk. sp. One specimen. 



The diameter of tlie disk is 4 mm. and the U^ngth of tlie arms, wlien measured 

 from their insertion on the thsk, is 5 mm. 



The upper face of the disk offers tlio phite arrangement so characteristic of 

 0. puhhcUum which has been described and figured by ]>yman; but on tbe under 

 face of the disk, in the interradial spaces, I observe a slightly different arrangement 

 from the one indicated by that author. Lyman point-s out that, following the 

 mouth slueld, the two genital plates are contiguous on a large part of their length, 

 and they are separated distally only by a median plate which occupies the margin 

 of the disk. On the specimen from the Alhatross the mouth shields have their 

 proximal angle more obtuse and the distal edge more rounded and convex. Each 

 of them is followed by a small, short, and rounded median plate which separates 

 the genital plates along a certain part of their interradial edge. Thanks to the 

 intercalation of that plate, which Lyman failed to mebtion, the two genital plates 

 remain contiguous only on a rather short space, since the}- are again distally 

 separated by the odd marginal plate, the only one which Lyman does mention on 

 the median interradial hne. I had already noticed, in the samples gathered by the 

 Travailleur and the Talisman, that this median plate was more elongated than in 

 Lyman's type (07 a, p. 260). I may add that, in the individual from the Albatross, 

 I have been able to identify the genital slits; these are extrenich^ short and carried 

 back toward the proximal end of the genital plates, but they are nevertheless 

 plainly recognizable. These slits had not been perceived b}' Lyman, who thought 

 they were lacking, and their discovery is all the more interesting owing to the 

 fact that they also exist in 0. speciosvm. 



OPHIOCTEN HASTATUM Lyman. 



See for bibhography: 

 Koehler (09), p. 165. 



Albatross station 2415. Apr. 1, 1885. Lat. 30° 44' X.; long. 79° 26' W.; 

 440 fathoms; co. crs. s. sh. for.; temp. 45.6° F. Two specimens. 



Albatross station 2429. June 13, 1885. Lat. 42° 55' 30" N.; long. 50° 51' W.; 

 471 fathoms; gy. m.; temp. 38.7° F. One small specimen. 



Albatross station 2542. July 7, 1885. Lat. 40° 00' 15" N.; long. 70° 42' 

 20" W.; 129 fathoms; s. brk. sh.; temp. 47.2° F. Two small specimens. 



Albatross stations 2582-83. Sept. IS, 1885. Lat. 39° 50' N.; long. 71° 43' W.; 

 131-137 fathoms; gn. m.; temp. 47.2° I*'. Many specimens mixed with numerous 

 OpJiioglypba sarsii. 



The diameter of the disk ranges between 3.5 and 10 mm., but is generalh- about 

 6 or 7 mm. 



