CLARK : A NEW GENUS OF OPHIURANS 385 



The other characters are essentially as in Ophiura (Ophioglypha). 



Range. — From the Antarctic regions in the vicinity of Cape Horn 

 northward along the coast of Chile to 38° 8' N. lat., in from 260 to 

 677 fathoms. 



Remarks. — In addition to the two species described below, this 

 genus includes Ophiomaria carinifera (Kcehler) and Ophiomaria doe- 

 derleini (Kcehler). 



Ophiomaria tenella, sp. nov. 



The disk is thin and stellate, the angles continuing uninterruptedly 

 into the arms, which taper very gradually and become very slender 

 distally. The disk is 11 mm. in diameter, and the arms are 40 mm. 

 long. 



The central portion of the dorsal surface of the disk is covered with 

 a close and regular fine granulation through which, in some specimens, 

 the six small rounded primary plates are visible. Toward the periph- 

 ery of the disk this granulation becomes coarser and more irregular, 

 the granules transforming into small flat polygonal plates. In the 

 center of the strongly excavated interbrachial margin of the disk, 

 as viewed dorsally, there is a transversely oval or semicircular plate, 

 usually about twice as broad as long; between this and the radial shields 

 on either side there is usually a plate about half as large, more or less 

 circular or irregularly polygonal in outline, and a few, very irregular, 

 much smaller plates. Within this interbrachial border, as within the 

 most proximal plates in the columns separating the radial shields, 

 there may be a few irregular polygonal plates bordering the granular 

 covering of the central portion of the disk. 



The radial shields are irregular rounded triangles, nearly or quite 

 twice as long as wide, about'as long as the width of the arm immediately 

 beyond the disk. The radial shields of each pair are separated interiorly 

 by a series of two or three plates of which the innermost is consider- 

 ably longer than the others; between this last and the granulation of 

 the center of the disk there are usually a few irregularly polygonal 

 plates of various sizes. From the distal end of the outermost plate 

 in the series between the radial shields there runs around the distal 

 borders of the latter a series of two or three or more irregular plates 

 (more rarely a double series) which takes the place of an arm comb. 

 The upper surface of these plates is even both with that of the radial 

 shields and with that of the arm plates beyond them. 



The interbrachial spaces below are filled with irregular polygonal 

 scales which are largest along the lateral bord?rs, becoming smaller 

 and more or less surrounded by or covered with granules centrally; 

 toward the oral shields they tend to imbricate more or less. 



The genital slits are long, reaching from a notch in the middle of 

 the sides of the oral shields to the border of the disk as viewed ven- 

 trally; they are bordered with small truncate closely crowded papillae. 



The proximal edges of the oral shields are straight and' make nearly 



