2 THE HANCOCK PACIFIC EXPEDITIONS VOL. 2 



Three specimens were taken shore collecting in a tide pool a 

 quarter mile south of Ritter's Landing at Black Beach, Charles Isle 

 of the Galapagos Islands, Station 199-34. 



Description. — Disk 13 mm. in diameter, arms 35-37 mm. long. 

 Disk covered with a coat of rather coarse scales, smaller ones min- 

 gled with the larger, the latter slightly swollen making the whole 

 surface rough and irregular; primary plates small but distinct; 

 radial shields very small, nearly or quite concealed by numerous 

 small disk scales; interradial margins of disk sharply defined by 5-7 

 large plates, of which the median is largest. Arm segments wider 

 than long; dorsal plates broken up into a large number (20-30) of 

 small polygonal plates of diverse sizes, forming a remarkably smooth 

 pavement continuous with the disk covering; the distal lateral plate 

 on each side is larger than the rest. Interbrachial areas below cov- 

 ered with fine scales; genital slits about equal to the three basal 

 arm segments. Oral shields pentagonal with lateral and distal cor- 

 ners rounded; madreporite nearly circular; adoral plates medium, 

 swollen, longer than the distal width, separated distally by the first 

 ventral armplate but meeting within; oral papillae five or six on each 

 side, penultimate twice as large as others. First under arm plate 

 small, triangular, or low pentagonal, succeeding plates squarish, as 

 wide as long. Side arm plate more or less covered, especially orally, 

 by a shagreen-like skin; each one bears three stout flattened, bluntly 

 pointed spines, as long as segment; lowest spine slightly the longest. 

 Tentacles scales three or four, two larger ones on proximal side of 

 pore and two or one much smaller on distal side; distally the scales 

 become less distinct and often only one is evident. 



Color in alcohol, disk cream yellow with irregular brown mark- 

 ings, in some of which the radial shields are usually included; arms 

 cream color with brown bands on every sixth segment; arm spines 

 nearly white; interbrachial areas below cream color speckled with 

 about a dozen dull purple spots; proximal ventral plates more or 

 less dusky; distally the brown bands of the arm are indicated by 

 dusky ventral plates. In the dried specimen the yellow tint is lost 

 and the disk and upper surface of the arms are a light grey with the 

 dark markings conspicuous. 



Types.— i:\iQ type is deposited at the United States Museum. The 

 co-types are deposited at: the Museum of Comparative Zoology, 

 Cambridge, Mass., number 4834; the Zoological Museum, University 



