CLARK: JAPANESE AND EAST INDIAN ECHINODERMS. 293 



3 or 4 basal under arm-plates wider than long; upper arm- 

 spine exceeding joint ; mouth shield pentagonal, lateral sides 



nearly equal to inner longispina. 



Tentacle scales wanting on all except basal pores, where there are 2 ; arm-spines 



3, short and peg-like inermis. 



Tentacle pores restricted to 3 basal joints of arm ; no tentacle scales present ; 3 

 minute arm-spines capensis. 



Ophioglypha sterea, sp. nov. 



Diameter of disc 7-8.5 mm.; length of arm 15-20 mm. Disc flat but high 

 (vertical diameter about 2 mm.), covered by rather more than 100 plates, among 

 which the centro-dorsal is conspicuous ; relative size and arrangement of dorsal 

 plates variable. Radial shields small, not much larger than centro-dorsal, about 

 as wide as long, broadly in contact ; inner ends separated very slightly by a 

 radial plate, outer ends distinctly separated by first upper arm-plate. — Arms 

 high and compressed at base, becoming nearly cylindrical towards tip. First 

 upper arm-plate nearly pentagonal with an angle between radial shields, about 

 half as large as one of them ; second plate quadrilateral, about twice as wide as 

 long ; these two plates are included in the disc notch ; third plate quadrilateral 

 with rounded corners, two or three times as wide as long ; next three or four 

 plates more or less hexagonal but wider than long and broadly in contact with 

 each other; succeeding plates longer than wide, gradually becoming diamond- 

 shaped with distal angle rounded; somewhere between fifteenth and twentieth 

 arm-joint, these dorsal plates cease to be in contact with each other. — Upper 

 ends of genital plates conspicuous dorsally on each side of base of arm, rounded, 

 flattened, and as wide as second dorsal arm-plate plus half of first ; each plate bears 

 an " arm-comb" of about a dozen spinelets, which are minute, flat, and truncate 

 ventrally, but become longer, cylindrical, and acute dorsally ; beneath this comb 

 (and naturally concealed by it) on margin of side arm-plate is a delicate fringe 

 of much more minute spinelets. — Ventral surface of disc with each interbrachial 

 space covered by oral shield and about a dozen small plates. Oral shields very 

 large (about 2 mm. long by 1.5 mm. wide), oval with narrow end inwards. 

 Adoral plates very small, with parallel sides. Oral plates larger than adoral, 

 somewhat swollen at inner end, and so forming a slight projection where they 

 meet. Oral papillae four or five on each side ; outermost widest and very flat, 

 next two or three short and blunt, innermost longer and pointed ; at apex of jaw 

 is an unpaired, pointed papilla, the longest of all. — First ventral arm-plate nearly 

 triangular with base and outer angle rounded ; next three or four plates a trifle 

 larger, more nearly square and broadly in contact ; next five or six are longer than 

 wide, more or less octagonal, and still in contact with each other; succeeding 

 plates are hexagonal, pentagonal, and finally nearly circular, and are widely sepa- 

 rated from each other. — Side arm-plates large ; high, broad, and flat near base 

 of arm where they meet neither above nor below ; they meet each other dorsally 

 somewhere after the fifteenth joint and ventrally two or three joints sooner. 



