388 BULLETIN 100, UNITED STATES NATIONAL MUSEUM. 



Notes. — The diameter of the disk varies between 9 mm. and 16 mm. 

 All the upper-arm plates are very regularly divided into two equal 

 halves by a longitudinal groove which sometimes bifurcates toward 

 the middle of the plate. *In the specimens from station 5444 the 

 mouth shields are entire, except in one, in which the proximal region 

 is separated from the rest by an oblique groove, and the large inter- 

 radial plate which follows the mouth shield is divided into two parts 

 in three interradii. In the two specimens from station 5618 all the 

 mouth shields are broken up into at least three fragments; but in 

 the largest specimen, which is from station 5445, neither the mouth 

 shields nor the plates which follow them are fragmented. 



I have already emphasized at different times ('04, p. 40; '07a, p. 

 262; '14, p. 18) the extent of the variations shown by O. inornata, 

 the geographical range of which is very great. It has been met with 

 in the three great oceans — the Atlantic, the Indian, and the Pacific. 

 In the Atlantic the Challenger found it in 1° N. latitude, 24° W. lon- 

 gitude, in 3,384 meters (1,850 fathoms), and the Albatross in 11° N. 

 latitude, 58° W. longitude, in 1,069 meters (880 fathoms). In the 

 Indian Ocean the Siboga found it at different stations in the Sunda 

 Archipelago between 470 and 1,264 meters (260 to 693 fathoms). In 

 the Pacific the Albatross dredged it between 0°-2° N. latitude and 

 90°-92° W. longitude, 2,175 to 2,487 meters (1,189 to 1,360 fathoms). 



OPHIOCTEN HASTATUM Lyman. 



Ophiocten hastatum Lyman ('78), p. 103, pi. 5, figs. 133, 134; ('82), p. 82, 

 pi. 9, figs. 10, 11.— Kceiileb ('98), p. 42, pi. 7, figs. 32, 33; ('09), p. 165; 

 ('14), p. 37.— H. L. Clabk ('15), p. 328. 



Ophiocten pacificum, Lutken and Mobtensen ('99), p. 131, pi. 3, figs. 5-7. — 

 H. L. Clakk ('11), p. 96; ('15), p. 328. 



Locality. — Albatross station 5080; off southern Japan; Omai Said 

 Light bearing N. 23^° E., 51.89 kilometers (28 miles) distant (lat. 

 34° 10' 30" K, long. 138° 40' 00" E.) ; 923 meters (505 fathoms) ; 

 October 19, 1906 ; fne. gy. S., Glob. 



One very small specimen (Cat. No. 40932, U.S.N.M.). 



Notes. — I certainly see no reason for separating from Ophiocten 

 hastatum O. pacificum, which Lutken and Mortensen described in 

 1899 from specimens collected at numerous stations between 0°-7° 

 N. latitude and 78°-86° W. longitude, at depths varying from 1,408 

 to 1,877 meters (770 to 1,573 fathoms). 



Ophiocten hastatum was met with in different localities in the 

 North Atlantic by the Hirondelle and the Princesse-AUce between 

 33°_40° N. latitude and 9°-30° W. longitude, at depths between 1,674 

 and 1,900 meters (917 to 1,040 fathoms). The Albatross captured it 

 between 30°^2° N. latitude and 50°-79° W. longitude, in 219 to 805 

 meters (120 to 440 fathoms). H. L. Clark records the species (under 



