322 BULLETIN OF THE 



disk, and over the arm on the outer edge of the radial shield. The edge 

 of the disk, in each interbrachial space, is composed above of three plates, 

 and below of six. 



Radial shields, of a very irregular triangular form, with the point inward ; 

 thoy nearly, or quite, touch without, but immediately diverge and are sep- 

 arated by a wedge of one small, one large, and part of another large plate; 

 length to breadth 1.5 : .8. Two small, rounded, tapering arm-spines; the 

 lower slightly longer; lengths to that of under arm-plates (5th joint) 

 A , .5 : .6. Tentacle scales, on second joint, six to each pore, arranged in 

 an oval, three on each side; on third joint, two, arranged side by side; 

 on joints beyond that, one. They all have the same shape of a small, 

 thickened scale, but those towards tip of arm are proportionately larger. 

 The mouth tentacles, of the first joint, have scales on either side, in form 

 of an incision, somewhat as in Ophioglypha : on the side next the jaw, the 

 two mouth-papilla? that stand on the side arm-plate are tentacle scales; 

 and, on the side next the mouth slit, there are two more, which stand on a 

 little plate, the homologue of a side arm-plate, running upwards into the 

 mouth slit from the first under arm-plate. 



Color, in alcohol, light brown. 



Two specimens, off Double-headed Shot Keys, in 315 fathoms. 



Ophiomusium, gen. now* 



Teeth : no tooth-papilla;; mouth-papilla: soldered in a continuous row, so 

 that their former outlines are scarcely to be seen. Disk covered by plates 

 and radial shields, all of which are intimately soldered, forming a surface 

 like porcelain. Upper and under arm-plates minute : side arm-plates meet- 

 ing above and below; swelled, intimately soldered with the neighboring 

 parts. No tentacle pores beyond the basal arm-joints. Small arm-spines 

 on outer edge of arm-plates. Two genital slits in each interbrachial space. 



In the nature ot its covering, this singular genus has some affinity with 

 Ophiolepis, as now restricted. But it is unique in having no tentacle pores 

 on the greater part of the arm. 



Ophiomusium eburneum Lyman, sp. nov. 



Special Marks. — Two \cvy small, blunt arm-spines, less than one third 

 as long as the arm-joint. No tent icles beyond the first two joints. Surface 

 of the disk and arm-plates microscopically granulated. 



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

 25 mm. Width of arm 1 mm. The mouth papillae, though closely soldered 

 to. each other, may be distinguished, in a partly dry specimen, by the light 



* 6</>is, snake; ^vtrelov, mosaic. 



