314 ART. 2. — H. MATSTJMOTO : 



ly small and very insignificant. Those following small, triangular, 

 with very large inner angle and very long, cont^ex outer border, 

 shorter than the corresponding arm joints, much wider than long ; 

 they become smaller and shorter outwards. All the arm plattes 

 are concentrically striated, as seen under the microscope. Six or 

 seven arm spines, spiniform, acute, slightly flattened, hyaline, 

 erect ; the uppermost one or two are nearly twice as long as the 

 corresponding arm joint, while the lowest one is slightly shorter 

 than the same. Single small, leaf-like, acate tentacle scale to 

 each pore. VertebrcX of the distal arm joints imperfectly divided 

 into halves by a series of pores. 



Colour in alcohol light yellow. 



This species is at once distinguished from both 0. miliaria 

 (Lyman) and pulverulenta (Lyman) by the fewer oral papilla?, by 

 the fewer and shorter arm spines and by the presence of only a 

 single tentacle scale to each pore. 



Ophiurodon Matsumoto, 1915. 



Disk, as well as radial shields, closely covered with fine 

 granules, sometimes bearing scattered spines. Oral angles and 

 oral shields also granulated. Four or five oral papillae on either 

 side, the outermost one projecting inwards above the next papilla. 

 Teeth very flat and widened, with very thin and translucent end, 

 arranged in a single vertical series. Dental papillas absent. Arms 

 not very long, widest at the base, tapering outwards to a very 

 slender tip. Dorsal and lateral arm plates usually concentrically 

 striated. Ventral arm plates very narrow, longer than wide, fully 

 in contact with one another. Vertebra? of the distal arm joints 

 often imperfectly divided into halves by a series of pores. More 



