MUSEUM OF COMPARATIVE ZOOLOGY. 239 



scales, nearly obscured by epidermis ; a large, round, primary scale in the 

 centre, surrounded by two and part of a -third rather irregular concentric 

 riivs of smaller ones ; from this central rosette radiate interbrachial bands, 

 each consisting of a line of three or four larger elongated scales, with a line 

 of about five narrower and smaller ones on each side ; the whole variable, 

 irregular, and much obscured by a thick epidermis. Along edge of disk, 

 outside radial shields, a cross line of about five large scales. Radial shields 

 smooth and fiat ; separated by a line of two or three scales ; length to 

 breadth 2:1. Interbrachial spaces below beset with minute spines, which 

 are encased in such a thick epidermis as sometimes to have a bead-like form: 

 they continue to the edges of the upper surface, but there are none in the 

 centre. Arm-spines seven ; a little out on the arm, six ; flattened, glassy : 

 the upper one slender, tapering, and with five or six thorns on each edge; 

 the lowest one formed like a stout double hook ; the rest with a smooth- 

 shaft much flattened at the end, where it has five to seven long thorns on 

 each edge, giving a wide brush-like shape to the tip, which is increased by the 

 thick epidermis investing the whole ; lengths to that of an upper arm-plate 

 (4th joint) 1.8, 1.8, 1, .G, .5, .4 : .6. At the very tip of arm, only three spines, 

 of which two are needle-like and the lowest one is a slender double hook. 

 Tentacle-scale well marked, with a sharp point. Color, above, pale purplish 

 blue with minute spots, or rings, of darker on the disk. 



Another specimen with disk of 7 mm. had the arm of 27 mm. The disk- 

 thorns were confined to the interbrachial spaces below. 



This species is easily recognized by its smooth, shiny disk, with little dark 

 rinirs, and its broad-ended arm-spines. 



Philippines, by Semper. Specimens also in Garden of Plants ; and, from 

 Makassar, at Berlin. 



Ophiothrix rudis sp. nov. 



Plate III., Figs. 11-14. 



Special Mart*. — Disk, above, except radial shields, closely sot with short, 

 very thick cylinders, jointed at their baseband having rounded ends. Seven 

 stunt, rounded, blunt, nearly smooth arm-spines ; the two upper ones much 

 the longest. 



Description of a Specimen. — Diameter of disk 9 mm. Length of arm 

 62 mm. Width of arm 2.2 mm. About thirty-five crowded tooth-papilla?, 

 whereof twenty-one form the border of tin- oval, and are much more project- 

 ing than the fourteen central ones. Mouth-shields wider than long, of a 

 broad, rounded diamond shape. Under arm-plates closely soldered to each 

 other; near base of arm. broader than long, of an irregular oval shape, with 

 a decided depression or re-entering curve within; length to breadth (8th 



