326 BULLETIN OF THE 



arm-plates broader without than within, and broader than long; on Cth 

 jointjlength to breadth 1 : 1.3. The plates lying within the disk are much 

 squeezed, laterally, by the large tentacles and their scales; beyond the 

 disk they have a more regular shape, with the outer side strongly curved. 

 Side arm-plates rather prominent, meeting above, but not below. Upper 

 arm-plates wide fan-shape, with outer side strongly curved, and coming to 

 a point within. Length to breadth 1: 1.7. Disk, with a well-marked, 

 round outline, standing oil' the bases of the arms; all its upper surface, 

 except the radial shields, beset with little, rounded, thorny knobs or 

 stumps, about -J mm. high ; they have a short, club form, like a folded toad- 

 stool, and bear a thorny crown ; there are about eight of these stumps to a 

 ; tpuare mm., where they are thickest. Interbrachial spaces below have like- 

 wise a few of these stumps. The sealing of the disk, in a partly dried 

 specimen, is easily seen. Radial shields of a blunt pear-seed shape, with a 

 rather irregular and ill-defined outline; they are slightly separated, and 

 are naked ; length to breadth 2.2 : 1.5. Genital slits large and extending 

 nearly to the margin of the disk. Arm-spines rough, and resembling 

 those of the smoother species of Opliiolhrix ; the five upper ones slender, 

 rounded, tapering gradually; the four lower ones somewhat flattened, 

 scarcely tapering, blunt; lengths to that of the under arm-plate (6th 

 joint) 3.8, 3.5, 2.5, 2.5, 2.2, 2.2, 2., 1.8, l.S : 1. Tentacle scales, two on 

 the first pores; after that only one; those at base of arm are large, thin, 

 longer than broad and cut square oil" at the tip : those further out are 

 much smaller and tend to become pointed, in alcohol, the specimens are 

 of a uniform faded straw-color. 



I ili a — A specimen with a disk of 9 mm. had only eight arm-spines 

 next the disk, and seven a little further out on the arm. The uppermost 

 spine is sometimes shorter than the second, but (he rest usually follow the 

 p oportions laid, down. In huge specimens the upper arm-plates have 

 their outer curve very prominent. 



This species has a rough resemblance to Opliiolhrix ro da: and the 

 genus has affinities with Opliiolhrix. The lowest arm-spine, on the very tip 

 joints, is a little curved and is strongly toothed on one edge, so as to form 

 a pat tial hook. 



Dredged off Sand Key, Florida, in 120 fathoms. 



Ophiomitra sertata Lyman, sp. nov. 



S cciul Marks. — Disk with small radial shields and beset with small 

 spines and grains. Sixteen mouth-papilla?. 



otion of a Specimen. — Diameter of disk 11 mm. Length of arm 



about 55 mm. "Width of arm between the joints 2 mm. Mouth-papilla; 



.• en i i each m mth-angle; two outer ones thin and nearly as wide 



