30 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 8 



the genital slits is a dark brown triangular splotch. Arms light buff with 

 a wide (2 segments), dark brown, almost black band, every 3 to 4 seg- 

 ments. Mouth parts and arm spines cream colored, slight traces of the 

 upper arm bands continue below. 



Types. — Holotype, AHF no. 7; 5 paratypes. 



Type locality. — Station 778-38, tide pool, Chatham Bay, Cocos 

 Island, Costa Rica, January 14, 1938. Five paratypes from Station 445- 

 35, shore, Panama City, Panama, February 2, 1935 ; one from Station 

 447-35, coral, Secas Islands, Panama, February 4, 1935 ; one from Sta- 

 tion 512-36, shore, Ballena Bay, Espiritu Santo Island, Gulf of Califor- 

 nia, February 23, 1936; one from Station 515-36, shore, San Francisco 

 Island, Gulf of California, Februarj^ 24, 1936; and one from Station 

 522-36, tide pool, Agua Verde Bay, Lower California, Mexico, Febru- 

 ary 27, 1936. 



Remarks. — In life the holotype had a bluish gray disk, reticulated 

 with light brown, much as in the West Indian O. reticulata (Say). The 

 very long arms, which were much broken in capturing the specimen, 

 were broadly banded with dusky purple. This species differs from other 

 eastern Pacific Ophionereis by the irregular coarse disk scaling, a uniform 

 series of 5 or 6 large marginal disk scales extending interradially from 

 the radial shields, large radial shields, and the distinct coloring of the 

 arms and disk. The name dictyota has been chosen because of the reticu- 

 lations on the disk. 



Ophionereis perplexa, new species 

 Plate 7, Figs. 7-9 



Description. — Disk diameter, 8 mm. ; arms, 42 mm. long. Disk more 

 or less depressed and irregular because of shrinkage upon drying. The 

 disk is covered by a membrane, which upon drying shows minute, dense, 

 overlapping, uniform scales, visible only under high magnification. No 

 primaiy plates are visible, and the scales bordering the radial shields and 

 disk margins are not enlarged or conspicuous. Radial shields small, nar- 

 row, more than 4 times as long as broad, acutely pointed within, widely 

 separated, distance apart exceeding the length of radial shields. The 

 minute overlapping scales obscure the outline of the radial shields. 



First upper arm plate small, semilunar, wider than long, proximal 

 margin straight, distal margin broadly convex, overlapping next plate. 

 Succeeding plates large, wider than long, basally triangular with rounded 

 corners, proximal margin slightly concave, distal margin convex, less 



