NORTH PACIFIC OPHIUBANS IN NATIONAL MUSEUM CLARK. 279 



ent scales. Oral papillae very few and small. Teeth reduced to a 

 small cluster at apex of jaw. No tentacle scales. 



Type-species. — OpJiioleptoplax megapora. 



The specunen upon which this genus rests is probably immature, 

 but I can not refer it to any known species or genus. In its mouth 

 parts it is very near Ophiosyzygus, but its arm structure is quite difTer- 

 ent. Yet I am not satisfied that the supposed upper arm j)lates are 

 really homologous with the upper arm plates of other genera. They 

 are certainly not calcareous and they may be nothing but skin 

 thickenings on each joint. Their appearance in this specimen may 

 be an individual peculiarity. 





Fig. 141.— Ophioleptopi.ax megapora. x S. a, from above; 6, from below; c, side ^^EW ok two 



ARM JOINTS NEAR DISK. 



OPHIOLEPTOPLAX MEGAPORA, new species." 



Disk 6 mm. in diameter; arms about 25 mm. long. Disk covered 

 with a thick, naked skin. Radial shields wanting, but upper ends 

 of genital plates are visible at base of each arm. Upper arm i)lates 

 represented by what appear to be very thin ti-ansparent noncalca- 

 reous scales, squarish in outline and rather wider than long; arm 

 bones plainly visible through them. Interbrachial spaces below 

 naked. Genital slits small. Oral shields very small, wider than long. 

 Adoral plates very large, much wider without than within. Oral 

 papilla, one to three on each side, minute, sharp conical spinelets. 

 Teeth (tooth papillae?) reduced to a small cluster at apex of jaw, of 

 very small, rough-pointed spinelets. Under arm plates longer than 



o Miyac, signifying big, and ndpoc, signifying a pore, in reference to the large tenta- 

 cle pores. 



