324 bulletin: museum of comparative zoology. 



pointed; the fourth and third are sHghtly flattened and blunt and 

 are minutely thorny at the tip. Tentacle-scale single, not peculiar. 

 Color, dry specimen, deep red, more or less variegated with whitish; 

 it is difficult to decide how much of the lighter areas is due to rubbing 

 off of the red skin, but certainl}^ some of it is; the radial shields and 

 radial plates are quite light and drstally are reddish white. 



The paratype, which is a little smaller, agrees well in all its struc- 

 tural features with the holotype but the coloration is very different. 

 The red color is confined to the center and interradii of disk; radial 

 shields and most of the upper arm -plates are dull green; a few scat- 

 tered arm-plates are light brown; under surface variegated with 

 greenish and white. 



This species is well-characterized by its short arms, with few but 

 long arm-spines, the nearly smooth disk with very large radial shields, 

 the wide upper arm-plates and the shape of the under arm-plates. 

 Its coloration is not reliable except in the absence of stripes or any 

 other definite markings. 



Ophiothrix leucotrigona, sp. nov. 



Xe/i/c6s = white + rplyoivov = triangle, in reference to the color-markings on 



the arms. 



Plate 5, fig. 2. 



Holotype.— M. C. Z., 3,988. Philippine Islands: Mindoro, Port 

 Galera, June, 1912. L. E. Griffin coll. 



Disk 5 mm. in diameter; arms about 20 mm. long. Disk covered 

 by a thick skin which completely conceals any scales but bears num- 

 erous low but rather slender bifid or trifid stumps. Radial shields 

 concealed by skin but apparently large, triangular, separated slightly 

 their whole length ; their surface is very smooth and nearly free from 

 stumps. Upper arm-plates diamond-shaped, with both proximal 

 and distal angles truncate and distal sides shorter than proximal; 

 distally they are quite swollen; the outlines are much obscured both 

 by skin and by the coloration but they seem to be distinctly longer 

 than wide, except perhaps at base of arm. Interbrachial areas below 

 covered by skin bearing a number of long and slightly rough spinelets. 

 Oral shields much wider than long, somewhat narrowly diamond- 

 shaped, with distal angle truncate and others rounded; proximal sides 

 a little concave; madreporite distinctly larger than the others. Adoral 



