230 BULLETIN 15, UNITED STATES NATIONAL MUSEUM. 



shields and characteristic adoral plates, with their spines, readily 

 distinguish it from that southern species. 



OPHIACANTHA BAIRDI. 



Ophiacantha bairdi I.yman, Bull. Mus. Comp. Zool., vol. 10, 1883, p. 256. 



Localities.— Albatross station 3070, off Washington, lat. 47° 29' 30'' 

 N.; long. 125° 43' W., 636 fathoms, green mud, bottom temperature 

 37.9°, 59 specimens; station 3338, off Alaska, lat. 54° 19' N.; long. 

 159° 40' W., 625 fathoms, green mud, sand, bottom temperature 

 37.3°, 2 specimens; station 3784, Bering Sea, lat. 54° 32' N.; long. 

 178° 31' E., 850 fathoms, green mud, fine gray sand, 78 specimens; 

 station 4767, Bering Sea, lat. 54° 12' N.; long. 179° 7' 30" E., 771 

 fathoms, green mud, bottom temperature 36.5°, 150 specimens; 

 station 4772, Bering Sea, lat. 54° 30' 30" X.; long. 179° 14' E., 344 

 to 372 fathoms, green-browTi sand, bottom temperature 38.1°, 1 

 specimen; station 4979, off eastern Japan, lat. 33° 53' N.; long. 137° 

 42' E., 943 fathoms, brown mud, fine sand, foraminifera, bottom 

 temperature 36.4°, 5 specimens. Bathymetrical range, 344 to 943 

 fathoms. Temperature range, 38.1° to 36.4°. Two hundred and 

 ninet3"-five specimens. 



Although Liitken and Mortensen'* have already recorded this 

 species from the Pacific Ocean and have given some excellent figures 

 of it, I have only been persuaded, after persistent comparison with 

 Lyman's West Indian s})ecimens, that these North Pacific specimens 

 are really hairdi. I am unable, however, to find any character in 

 which the Pacific specimens consistently differ, nor is there the 

 slightest difference between the specimens from station 4767 and 

 those from station 4979. The geographical range of hairdi is there- 

 fore astonishing, -extending from the eastern Atlantic {Travailhur 

 coll.), through the Caribbean Sea and Gulf of Panama, westward to 

 Japan and northward to Alaska. In Liitken and Mortensen's fig- 

 ures, already referred to," the arm spines are rather heavy. All of 

 the specimens before me have very slender and sharp arm spines. 

 Koehler ^ speaks of hairdi as having two tentacle scales, whereas Lyman 

 definitely says, and Liitken and Mortensen clearly figure, one; none 

 of the specimens before me have more than one, even on the first 

 arm pores. This species is very near OpTiioconis, and it is virtually 

 impossible to find any character which would warrant their being 

 placed in separate families, yet our present system of classification 

 severs them wddely. There is not a little individual diversity in the 

 relative abundance of spines and granules on the disk of hairdi. In 

 some specimens there are no granules sufficiently elongated to be 



oMem. Mus. Comp. Zool., vol. 23, 1891, p. 177. 

 bSiboga Oph. Mer Prof., 1904, p. 119. 



