NORTH PACIFIC OPHIURANS IN NATIONAL MUSEUM CLAEK. 63 



lat. 33° 53' N.; long. 137° 42' E., 943 fathoms, brown mud, fine sand, 

 foraminifera, bottom temperature 36.4°, 4 specimens; station 5030, 

 Okhotsk Sea, hit. 46° 29' 30" N.; kmg. 145° 46' E., 1,800 fathoms, 

 brown mud, bottom temperature?, 2 specimens; station 5083, off 

 Omai Saki light, lat. 34° 4' 20" N. ; long. 137° 57' 30" E., 624 fathoms, 

 fine gray sand, globigerina, bottom temperature 38.1°, 2 specimens; 

 station 5084, off Omai Saki light, lat. 34° N.; long. 137° 49' 40" E., 

 918 fathoms, green mud, fine sand, globigerina, bottom temperature 

 36.8°, 2 specimens. Bathymetrical range, 624 to 1,800 fathoms. 

 Temperature range, 38.1° to 35.1°. Sixteen specimens. 



This excellent series of specimens, ranging in size from a disk diame- 

 ter of 7 mm. to one of 33 mm., has been carefully compared with the 

 Blalce specimens of irrorata from the Caribbean Sea and the Challenger 

 specimens of irrorata from off the coast of Australia and the coast of 

 Portugal, with a cotype of orhiculata from Japan, with a cotype of 

 grandis from Albatross station 2573, and with specimens of tumulosa 

 from the Albatross collection in the Panamic deep-water region, and 

 I am fully satisfied that these four nominal species are in reality one 

 and the same. Moreover, I see no character by which involuta can 

 be distinguished, and I have accordingly included that name as a 

 synonym. It seems, therefore, that in irrorata we have a cosmopolitan 

 deep-water species, like Ophiomusium lyrnani, and it is of some interest 

 to note here the various stations at which it has been taken: Off 

 New England, off Portugal, in the West Indies, southeast of the Cape 

 of Good Hope, in the Bay of Bengal, off New South Wales, off Japan, in 

 Bering Sea, in the Gulf of California, in the Gulf of Panama, and 

 among the Galapagos Islands. Except the very young specimens 

 taken by the Cliallenger off New South Wales, and regarding the 

 identification of which some doubt might reasonably be raised, speci- 

 mens have not been taken in less than 600 fathoms, and the species 

 ranges from that depth to over 2,200 fathoms. In spite of its exten- 

 sive geographical and bathymetrical range, the species is not remark- 

 ably variable, the differences with which the various names have been 

 associated being mainly due to size or age. In the 3'oung, the arm 

 spines even at the base of the arm are about equally spaced, but in 

 larger specimens the upper one becomes widely separated from the 

 other two. If, however, we follow the arm of an adult from base 

 to tip, we find the spines gradually approaching each other, so that 

 at the tip of the arm in a big specimen the arm spines correspond to 

 those at the base of the arm in a young specimen, an interesting illus- 

 tration of a "localized stage." In all adult specimens, however, the 

 middle arm spine at the tip of the arm terminates, as Lyman pointed 

 out, in a hook. The size of the arm spines differs greatly in (Hfi'crent 

 individuals, })ut these differences do not seem to be correlated with 

 size, or locality, or depth. The shape of the oral shields and of the 



