200 BULLETIN 75, UNITED STATES NATIONAL MUSEUM. 



and equals two or three joints. Tentacle scale single (sometimes two 

 on basal pores), moderate, rounded or bluntly pointed. Color (dried 

 from alcohol), nearly white, or bright brownish-yellow, or brownish- 

 gray. 



Localities. — Albatross station 3480, Bering Sea, lat. 52° 6' N. ; long. 

 171° 45' W., 283 fathoms, black sand, coral, rocky, 3 specimens- 

 station 4769, Bering Sea, lat. 54° 30' 40" N. ; long. 179° 14' E., 237 

 to 244 fathoms, gray sand, green mud, bottom temperature 38.5°, 2 

 specimens; station 4771, Bering Sea, lat. 54° 30' N. ; long. 179° 17' E., 

 426 fatlioms, broken shells, 1 specimen; station 4772, Bering Sea, lat. 

 54° 30' 30" N.; long. 179° 14' E., 344 to 372 fathoms, green-brown 

 sand, bottom temperature 38.1°, 3 specimens; station 4797, Sea of 

 Okhotsk, lat. 52° 37' 30" N. ; long. 158° 50' E., 68 fathoms, green 

 mud, coarse black sand, broken shells, bottom temperature 36.6°, 1 

 specimen; station 4809, Sea of Japan, lat. 41° 18' N.; long. 140° 8' 40" 

 E., 90 to 207 fathoms, gray sand, broken shells, pebbles, 2 specimens; 

 station 4828, Sea of Japan, lat. 37° 23' N.; long. 137° 36' E., 163 

 fathoms, green mud, bottom temperature 34.9°, 1 specimen; station 

 5085, Sagami Bay, lat. 35° 6' 45" N.; long. 139° 19' 45" E., 622 

 fathoms, green mud, fine black sand, bottom temperature 37.8°, 1 

 specimen. Bathymetrical range, 68 to 622 fathoms. Temperature 

 range, 38.5° to 34.9°. Fourteen specimens. 



Type.— C&t. No. 25543, U.S.N.M., from station 4772. 



Some specimens of this species seem to be so near to 0. pentagona 

 that I have been in great doubt as to whether the species ought to 

 be considered different or not, but as they are mostly from much 

 more northern stations, I have decided to establish it. It may be 

 recognized by the following characters: The adoral plates are much 

 narrower and thinner than in pentagona, the oral papillae are nar- 

 rower and more delicate, the tentacle scale is larger and more obtuse, 

 the upper arm plates are smaller and more triangular, the arm 

 spines are a trifle shorter and thicker, and the disk stumps are much 

 longer and slenderer. Unfortunately no one of these characters is 

 so constant as to form an unfailing mark of distinction, yet when 

 all are taken into account the two species are distinguishable. The 

 tentacle scales and disk stumps furnish the best characters, par- 

 ticularly in adults. (Comparison of the figures given here with the 

 figures of pentagona given by Koehler "■ will serve to emphasize the 

 resemblances, rather than the differences, between the two species. 

 The largest specimen of adiapTiora before me is 9 mm. across the 

 disk and is remarkable for having six arms and six jaws; it is not 

 otherwise peculiar. 



a Investigator Deep Sea Oph., 1899, pi. 4, figs. 27-29. 



