160 BULLETIX OF THE 



OPHIOSCIASMA* gen. nov. 



Disk covered vdth thick soft skin finely graniilated. Arms very slender, 

 ■with lower and side plates imperfectly calcified, and no upper plates. Mouth- 

 papillte and teeth represented by a bmich of spines, or thorns, at apex of jaw. 

 Arni-spmes arranged on sides of side arm-plates. Two large genital openings 

 in each interbrachial space. 



A singular genus, which, by its disk covered with soft skin and lack of up- 

 per arm-plates, is allied to Ophioscolex, but difi'ers by its granulation, and its 

 extremely slender, knotted arms. 



Ophiosciasma attenuatum sp. nov. 



Plate TU. Fiss. 193-196. 



Special Marks. — Disk beset with a very fine but not continuous granula- 

 tion. Arms very slender, knotted, and at centre of the joints diaphanous. 

 Three small nearly equal arm-spines. 



Description of an Individual (Station 122). — Diameter of disk 6 mm. 

 Length of arm 45 mm. Width of arm -without spines .6 mm. Mouth-papillce, 

 teeth, and tooth-papiUae combined in form of a clump of seven or eight sharp 

 thorns or spines, standing round the apex made by the juncture of the long 

 narrow mouth-frames. Mouth-shields of a transverse diamond-shape, very 

 small, sometimes scarcely visible, more or less hidden by thick skin. Side 

 mouth-shields very narrow and slender, meeting Avithin. Under arm-plates 

 very thin, and in their central part transparent, so that their outlines are 

 vague ; longer than broad, with outer side slightly curved and lateral sides 

 re-enteringly curved ; length to breadth .5 : .4. Side arm-plates reduced to 

 a strip, like a double cord, nmning along the side of the joint. No upper 

 arm-plates. The arm-bones are but slightly calcified, except at their thick- 

 ened ends, so that their more slender central shaft is translucent. The arm 

 thus presents a beaded appearance, with swellings where the ends of the 

 arm -bones form joints and support the arm-spines. Disk covered with a 

 thick skin, which above is beset with fine grains, and which partially obscures 

 the moutli-papillce and the arm-spines. No radial shields or disk-scales visi- 

 ble. Three small, blunt, nearly equal arm-spines, not so long as an arm-joint, 

 seen to be microscopically rough when free of skin, and standing nearly at 

 right angles to arm. Tentacles large, simple, and fleshy ; no tentacle-scales. 

 Color in alcohol, very pale yellow. 



Station 122, 350 fathoms, 1 specimen. 



* 6<pis, snake ; ffKidafia, shadow. 



