RECENT OPHIURANS. 247 



634. A.LIMBATA(Grube). Plate 8, f. 3, 4. 

 Ophiolepis limbala Grube, 1860. Nov. act. Acad. Caes. Leop., 27, p. 34. 



3 specimens. Brazil: Rio Janeiro. 



635. A. MAGRASPIS H. L. Clabk, 1911. Bull. 75 U. S. N. M., p. 157, f. 66. 



15 PAEATYPES. Off Washington, 115 fms. Off eastern Japan, 501-749 

 fms. 



636. A. MESOPOMA, sp. nov. {ixt^os, middle + wana, lid). Plate 6, f. 11-14. 



Disk 7 mm. in diameter; arms about 55 mm. long, rather wide at base and 

 tapering evenly to tip. Disk covered with a coat of rather coarse scales, with 

 the six primary plates forming a compact group at center; from this group to 

 margin of disk one may count about 10 series of scales, and about the same 

 number across an interradial area between the radial shields. The latter are 

 small and narrow, 1.5 mm. long by .5 mm. broad; they are nearly parallel and 

 separated for their entire length. Upper arm-plates very wide and in contact 

 for their full breadth throughout; the length of each is about one third the width; 

 the distal corners are rounded. The interbrachial areas- below are fully covered 

 with coarse scales. Oral shields (except madreporite) narrow, longer than wide, 

 somewhat triangular with the short distal margin strongly convex, the other 

 two sides quite straight ; madreporite large and swollen, nearly circular. Adoral 

 plates slender triangular, one angle separating the oral shield from the side arm- 

 plate, a second in contact with the first under arm-plate and the third meeting 

 its feUow proximal to the oral shield. Oral papillae 3 on a side, the middle one 

 largest and hd-like (hence the name) ; subdental pair, close together, thick and 

 squarish; distal pair scale-Uke, somewhat smaller than middle pair. Under 

 arm-plates squarish, the first one very small, the succeeding ones moderately 

 large, as long as wide but becoming wider than long at middle of arm and finally 

 longer than wide at tip; all quite closely in contact. Side arm-plates low and 

 small; each carries three arm-spines of subequal length, rather longer than an 

 arm-joint; upper and lower spines more or less pointed and little flattened, but 

 middle spine, especially near middle of arm, flat, broad, and truncate. Tentacle- 

 scales 2, large, subequal; the scale borne on under arm-plate equals that plate in 

 length. Color in life, disk fawn-colored with here and there orange-brown 

 markings; arms whitish; dried from formaUn and corrosive sublimate, the disk 

 is pale yellowish gray, the arms dirty whitish. 



Holotype (M. C. Z. 3740). Torres Strait: Badu, under a rock in a few 

 feet of water near shore. Nov. 1, 1913. Carnegie Exp., 1913. F. A. Potts coll. 



