NORTH PACIFIC OPHIURANS IN NATIONAL MUSEUM CLARK. 285 



six arms. The specimens under 5 mm. across the disk all have six 

 arms, except two which have seven, while those above that size have 

 only five. Furthermore, the six arms are not of equal size, but three 

 are large and three are small, often very small, indicating that repro- 

 duction by fission has taken place. None of the specimens reveals 

 how the six-armed young becomes the symmetrical five-armed adult, 

 but in two specimens the middle arm of the smaller trio is distinctly 

 smaller than its two neighbors, and it may be that this middle arm is 

 ultimately resorbed or lost by autotomy. The study of the actual 

 development of Astroceras, taking into account the plane of sym- 

 metry of both larva and adult, would prove most interesting and 

 important. 



ASTERONYX LOVENI. 



Asteronyx loveni MULLER and TROSCHEL, Sys. Ast., 1842, p. 119. 



Localities. Albatross station 2860, off Washington, lat. 51 23' N. ; 

 long. 130 34' W., 876 fathoms, green mud, bottom temperature 36.5, 

 65 specimens; station 2861, off Washington, lat. 51 14' N.; long. 

 129 50' W., 204 fathoms, bottom temperature 42.6, 3 specimens; 

 station 3069, off Washington, lat. 47 25' 30" N.; long. 125 42' W. 7 

 760 fathoms, green mud, bottom temperature 37.6, 3 specimens; 

 station 3075, off Washington, lat. 47 22' N.; long. 125 41' W., 859 

 fathoms, green mud, bottom temperature 36.6, 13 specimens; station 

 3112, off California, lat. 37 8' N.; long. 122 47' W., 296 fathoms, fine 

 gray sand, bottom temperature 41.8, 40 specimens; station 3126, off 

 California, lat. 36 49' 20" N.; long. 122 12' 30" W., 456 fathoms, 

 green mud, bottom temperature 42.8, 3 specimens; station 3128, off 

 California, lat. 36 41' 50" N.; long. 122 7' 30" W., 627 fathoms, 

 blue mud, bottom temperature 38.9, 4 specimens; station 3338, off 

 Alaska, lat. 54 19' N.; long. 159 40' W., 625 fathoms, green mud, 

 sand, bottom temperature, 37.3, 277 specimens; station 3489, 

 Bering Sea, lat. 57 N.; long. 173 14' W., 184 fathoms, green mud, 

 gray sand, bottom temperature 38.5, 4 specimens; station 3670, off 

 Monterey, CaL, lat. 36 43' N.; long. 122 12' W., 581 fathoms, green 

 mud, sand, bottom temperature 37.8, 1 specimen; station 3749, off 

 Suno Saki, Honshu Island, Japan, 83 to 158 fathoms, black sand, 

 shells, 16 specimens; station 3784, Bering Sea, lat. 54 32' N.; long. 

 178 31' E., 850 fathoms, green mud, fine gray sand, 1 specimen; 

 station 4781, Bering Sea, lat. 52 14' 30" N.; long. 174 13' E., 482 

 fathoms, fine gray sand, pebbles, bottom temperature 38.6, 1 sped-' 

 men; station 4957, off southern Japan, lat. 32 36' N. ; long. 132 23' E., 

 437 fathoms, green-brown mud, fine gray sand, foraminifera, bottom 

 temperature 39.8, 2 specimens; station 4959, off southern Japan, lat. 



a The name has very commonly been contracted to "Astronyx," but as Mtiller and 

 Troschel's spelling is philologically correct it ought to be retained. 



