1915.] NATURAL SCIENCES OF PHILADELPHIA. 49 



Ophiohyalus gotoi sp. nov. 



Diameter of disk 9 mm. Length of arms 28 mm. Width of 

 arms at base 1 mm. Disk pentagonal, with concave interradial 

 borders, very fiat, covered by a thin skin. Marginal disk scales 

 present, feeble. Radial shields rudimentary and insignificant, 

 forming a continuous row with the marginal disk scales. Genital 

 slits small and short, extending from outer end of adoral shield to 

 that of second lateral arm plate. 



Oral shields triangular, with perfectly rounded lateral angles, 

 outer side slightly concave; two and a half times as wide as long. 

 Adoral shields large, triangular, very long, acutely tapered inwards, 

 but not meeting. Oral plates long and narrow. The space encircled 

 by the oral and adoral shields and oral plates is strongly depressed. 

 Three or four oral papillse on either side, thin, hyaline, serrate along 

 the free edge. Two or three short, wide, flattened teeth, with 

 rounded and finely serrate ends. Deep in the oral slit on either side 

 of each jaw there occurs one conical, rough papilla, which protects 

 the first oral tentacle pore. 



Arms slender, covered by a very thin, transparent skin. Dorsal 

 arm plates small, oval, thin, hyaline, longer than wide, wider within 

 than without, separated from each other by naked spaces; the}^ lie 

 over the distal parts of the vertebrae of the corresponding arm joints, 

 and become very small and delicate towards the extremity of the 

 arm. Lateral arm plates low, slightly flaring, successive plates not 

 in contact with each other, but separated by a naked space, which 

 is widened upwards and continued into a large naked space bounded 

 by the dorsal and lateral arm plates and the vertebra. First ventral 

 arm plate not very small, quadrangular, with strongly curved outer 

 side, much wider without than within; those beyond nearly rhom- 

 boidal in outline, with a conspicuous reentrant notch at outer end 

 and a half pore for the tentacle at each lateral angle; much longer 

 than wide, widest opposite outer ends of tentacle pores; successive 

 plates not in contact with each other, except within the disk. The 

 lateral arm plates do not, however, meet each other in the ventral 

 median line, so that there is left here a naked, depressed space, which 

 is especially well-marked near the extremity of the arm. Except 

 within the disk and at the very base of arms, the vertebrae are more 

 or less or entirely divided into halves by fusiform pores, which 

 become larger and longer in the more distal part of the arm. Arm 

 spines two, sub ventral, unequal, glassy, all converted into compound 

 hooks, with a series of booklets along their ventral side, covered by 



