32 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 8 



Albemarle Island, Galapagos, February 13, 1933; 2 from Station 202-34, 

 shore, Osborn Island, Galapagos, January 31, 1934; one from Station 

 313-35, shore, Black Beach Anchorage, Charles Island, Galapagos, De- 

 cember 6, 1934; 3 from Station 342-35, shore, Bartholomew Island, Ga- 

 lapagos, December 12, 1934; 12 from Station 350-35, shore. South Sey- 

 mour Island, Galapagos, December 13, 1934; 7 from Station 351-35, 

 shore, Charles Island, Galapagos, December 14, 1934; one from Station 

 515-36, shore, San Francisco Island, Gulf of California, Februaiy 24, 

 1936; 6 from Station 530-36, 10-20 fms., ofif San Francisquito Bay, Low- 

 er California, Mexico, March 1, 1936; 2 from Station 719-37, 10-25 

 fms., Consag Rock, Lower California, Mexico, March 24, 1937; 5 from 

 Station 782-38, shore, Darwin Bay, Tower Island, Galapagos, January 

 16, 1938; 29 from Station 784-38, shore. Tower Island, Galapagos, Jan- 

 uary 17, 1938; 3 from Station 789-38, shore. South Seymour Island, 

 Galapagos, January 19, 1938; one from Station 795-38, 30-40 fms., 

 Sulivan Bay, James Island, Galapagos, January 21, 1938; 2 from Station 

 796-38, shore, Sulivan Bay, James Island, Galapagos, January 21, 1938; 

 4 from Station 800-38, shore, Cartago Bay, Albemarle Island, Galapagos, 

 January 22, 1938; 3 from Station 803-38, shore. Black Beach, Charles 

 Island, Galapagos, January 23, 1938; one from Station 808-38, shore, 

 Academy Bay, Indefatigable Island, Galapagos, January 25, 1938; and 

 2 from Station 400-35, shore, Manta, Ecuador, January 19, 1935. 



Remarks. — This species is rather common in the Galapagos Islands 

 and differs from the other members of the genus by its exceedingly fine 

 disk scaling, radial shields which are separated more than their length 

 apart, lack of genital papillae, absence of enlarged scales about the disk 

 margin and radial shields, and coloring. From O. annulate (Le Conte) 

 and O. dictyota it differs by lacking large disk scales about the radial 

 shields and disk margins. Its 3 arm spines distinguish it from O. albo- 

 maculata Smith and O. eurybrachtplax H. L. Clark, which basally have 

 4. From its closest ally, O. nuda Liitken and Mortensen, it can be dis- 

 tinguished by its arm length, 4 oral papillae, presence of fine scales, lack 

 of genital papillae, and uniquely separated radial shields. In a series of 

 64 are a number of variations ; in some specimens the disk below is cov- 

 ered by a naked membrane, and in others the upper disk scaling is continu- 

 ous to the adoral plates. Of the 64 specimens, 45 had 4 oral papillae on 

 each side ; 7 had 3 on one or more jaw sides and 4 on the remaining sides ; 

 and 4 had 4 oral papillae with either of the 2 middle papillae divided into 

 2 or 3 spiniform papillae, with a common base. The name perplexa has 



