244 



BULLETIN 75, UNITED STATES NATIONAL MUSEUM. 



Localities. Albatross station 3599, Bering Sea, lat. 52 5' N.; 

 long. 177 40' E., 55 fathoms, rocky, fine sand, shells, 56 specimens; 

 station 3785, Bering Sea, north of Rat Islands, 270 fathoms, gray 

 sand, broken shells, 1 specimen; station 4771, Bering Sea, lat. 54 

 30' N.; long. 179 17' E., 426 fathoms, broken shells, 2 specimens; 

 station 4781, off Agattu Island, lat. 52 14' 30" N.; long. 174 13' E., 

 482 fathoms, fine gray sand, pebbles, bottom temperature 38.6, 

 22 specimens; station 4782, off Attu Island, lat. 52 55' N.; long. 

 173 27' E., 57 to 59 fathoms, rocks, gravel, 2 specimens; station 4784, 

 off Attu Island, lat. 52 55' 40" N.; long. 173 26' E., 135 fathoms, 

 coarse pebbles, 14 specimens; station 4809, Sea of Japan, lat. 41 

 18' N.; long. 140 8' 40" E., 90 to 207 fathoms, gray sand, pebbles, 

 broken shells, 4 specimens. Bathymetrical range, 55 to 482 fathoms. 



FIG. 117. OPHTOLEBES TYLOTA. x 5. a, FROM ABOVE; 6, FROM BELOW; c, SIDE VIEW OF TWO ARM JOINTS 



NEAR DISK. 



Temperature range, ? to 38.6. One hundred and one specimens. 



Type. Cat. No. 25726, U.S.N.M., from station 3599. 



The characteristic disk-covering and arm spines are quite sufficient 

 to distinguish this from any of the other species, but it must be con- 

 fessed that the preceding species (pachylactra} is very closely related. 

 The differences shown by the arm spines are of degree rather than of 

 kind, but I find it hard to believe that the same is true of the disk 

 spines. Possibly pachylactra is a "mutant" from tylota. The 

 specimens from station 4809 are almost exactly like those from 

 station 3785, but have the disk spines much shorter than in the type. 

 It is remarkable that this species should have been taken so far 

 south as at station 4809, and one can not avoid suspecting the label. 



