238 BULLETIN OF THE 



line of the radial shields may be distinguished, because they bear fewer 

 stumps. Under the microscope the disk has a luuk uf being sprinkled with 

 little glass stars, among which appears, very rarely, a short spine. Below, 

 the interbrachial spaces are naked at their inner angle, but towards the mar- 

 gin are beset with cylindrical spines which are about ^ mm. lone, while the 

 stumps are not over i mm. Genital plates wide, at outer end of the open- 

 ings. Ann-spines about eight, short, glassy, flattened, and rather blunt, 

 about as in 0. exigua ; the longer ones have six to nine well-marked thorns 

 on each edge, and three minute thorns at the tip ; lengths to that of an upper 

 arm-plate (7th joint) 1.8, 2, 2, 1.8, 1, .8, .6, .5 : .0. The lowest spine retains 

 the form of a triple hook quite to base of arm. Tentacle-scales blunt, small 

 but distinct. Color, above, disk indigo round margin, paler towards centre ; 

 upper arm-plates mottled blue and white, with an ill-marked central line : 

 lower surface paler. 



This stands near O. carlnata v. Mart., but the disk-stumps with their star- 

 like crowns, the disk-spines below, the more numerous arm-spines, and dif- 

 ferent upper arm-plates, will separate it from tins, as well as from 0. exigua 

 and 0. purilla. 



Philippines, by Semper ; also from Borneo, in the Hamburg Museum. 



Ophiothrix plana sp. nov. 



Plate IV., Figs. 1 - 8. 



Special Marks. — Bisk smooth and covered by a thick epidermis, through 

 which the scaling and the outlines of radial shields are seen vaguely. Near 

 edge and on interbrachial spares below, short thorns covered with so thick 

 an epidermis as often to be bead-like in form. Color of disk pale blue, 

 with minute darker rings. Seven arm-spines, all. usually, with widened 

 ends, except the upper one, and covered with a thick epidermis. 



Description of an Individual. — Diameter of disk 6.5 nun. Length of arm 

 32 mm. Width of arm 1.5 mm. Tooth-papilla; eighteen, of which fifteen 

 form the bonier of the oval, and three much shorter ones a single line in the 

 centre; all the papillae, except lowest, quite stout. Mouth-shields small, 

 oval, with a peak within, and closely soldered with surrounding parts. 

 Under arm-plates squarish, with rounded corners and a re-entering curve 

 without ; length to breadth (8th plate) .0 : .7. Side arm-plates well marked, 

 but small, and lying close to arm. Upper arm-plates small and swelled, 

 bounded without by a wide curve; on the sides by slightly re-entering curves 

 which converge strongly, leaving the inner side very short ; length to breadth 

 (8th plate) .G : 1. At the very tip of arm, the side arm-plates meet above, 

 but not below. Bisk nearly smooth, with radial shields rather small and on 

 a level with the rest of the surface ; the centre occupied by a rosette of thin 



