236 BULLETIN OF THE 



arm-plate. About nine short arm-spines, of which the lowest continues as a 

 hook quite to base of arm. Disk densely beset, radial shields and all, with 

 very short, even, forked stumps. 



Description of an Indlcldual. — Diameter of disk 5 mm. Length of arm 

 1G mm. Width of arm 1 mm. Tooth-papillae of usual form, arranged in an 

 oval, whose border is made up of about eleven papilla? with a central, single 

 line of three or four papillae. Mouth-shields small, indistinct ; of a rounded 

 diamond shape. Under arm-plates as long as broad, squarish, with a notch 

 in their outer side ; they are obscured by thick skin, and are somewhat sep- 

 arate'. Side arm-plates stout and pretty strongly projecting ; each one has 

 a triangular piece projecting towards and near the upper arm-plate. Upper 

 arm-plates swelled and very distinct, longer than broad, narrow, of an oval 

 diamond shape. Near the base of arm they touch, but near the end they 

 are separated, and. the side-plates being very projecting, there appear con- 

 siderable naked spaces on the arm. Disk densely and evenly beset, above 

 and below, with minute, forked stumps about .4 mm. high, so that no trace 

 of radial shields is seen. These stumps are very short, and consist of a little 

 trunk with a diverging crown of three, four, or live sharp, slender prongs. 

 Those of the interbrachial spaces below are somewhat longer in the trunk, 

 and a few, towards the mouth, have only short blunt thorns. Genital scales 

 at outer end of openings very broad, and nearly meeting over the arm. 

 Arm-spines short ; near base of arm, nine ; of which the lowest is a triple 

 hook. Lengths, to that of an upper arm-plate, .7, 1, 1, 1, ,8, .6, .5, .4, .3 : .6. 

 The five upper are tapering, rather slender and glassy, with three to six 

 sharp, not very long, thorns on each side. The three lower are blunt, with 

 two to five blunt thorns at their tip. Close to tip of arm there is only a 

 larii'e triple hook, above which is a short and very feeble spine. Tentaclc- 

 scale none, or so feeble as to be scarcely visible. Color pale blue, in alcohol. 



Philippines ; by Semper. Specimens also in Garden of Hants. 



Ophiothrix exigua sp. nov. 



Plate IV., Figs. 24 - 2G. 



Special Marks.- — Upper arm-plates thick, distinct: as broad as long; 

 curved without. About seven short arm-spines, of which the lowest con- 

 tinues as a hook to the base of the arm. Disk above densely beset, radial 

 shields and all, with very short, even, forked stumps, but naked below. 



Description of an Indlcldual. — Diameter of disk 5 mm. Length of arm 

 17 mm. Width of arm 1.1 mm. Tooth papilla? arranged in an oval whose 

 border is composed of about eleven papilla', with a central line of three. 

 They are more pointed and less crowded than in 0. pusllla. Mouth-shields 

 much wider than long, and of a diamond shape, with rounded angles. Under 



