308 bulletin: museum of comparative zoology. 



rounded triangular as wide as long or wider. Adoral plates elongated 

 triangular, nearly or quite meeting radially but not interradially, 

 where they are more or less separated by the oral shield; the distal 

 angle does not extend down between the oral shield and the side arm- 

 plate. Oral papilla one on each side, large and nearly circular. Under 

 arm-plates pentagonal or hexagonal; near middle of arm, they are 

 distinctly pentagonal with a sharp proximal angle, the three distal 

 sides slightly concave, and the distal angles rounded; they are longer 

 than 'Aade and barely in contact ; basally, however, they are more and 

 more broadly in contact and hence become hexagonal and some at 

 least are wider than long. Side arm-plates low and small; each 

 carries a series of 4 (or 3) short, thick, blunt spines, scarcely as long 

 as the arm-segment; the uppermost or next lower is biggest. Ten- 

 tacle-scale 1, large and oval. Color, in life and in dried specimens, 

 which have not been in alcohol, variegated dull bluish green and 

 whitish, with irregular spots and markings of a dull blue. The colors 

 are little affected by alcohol. 



This little Ophiactis occurs with 0. lyviani and 0. savignyi in great 

 numbers in the coralline Algae in the shallow parts of Buccoo Bay. 

 It is always easily recognizable by the blue color but it was not until 

 preserved material was critically studied that it became evident it is 

 not a mere form of 0. samgnyi, as was supposed when the material 

 was gathered. The presence constantly of only one oral papilla 

 and the entire absence of swelling or notching of the upper arm-plates 

 are good evidence that 0. cyanostida is not identical with 0. savignyi 

 and the single oral papilla separates it from young 0. mulleri even 

 regardless of the distinctive coloration. 



Ophiactis quadrispina. 

 H. L. Clark, 1915. Mem. M. C. Z., 25, p. 264, pi. 10, fig. 9, 10. 



This species is known only from the Philippine Islands. 



Ophiactis conferta. 

 Koehler, 1905. SiBOGA-exp. Oph. litt., p. 25, pi. 3, fig. 15-17. 



The only known locality for this species is near the island of Sala- 

 watti, Dutch East Indies, in 10 fms. 



