NORTH PACIFIC OPHIURANS IN NATIONAL MUSEUM CLARK. 



163 



shields long and narrow, separated throughout or barely touching 

 distally. Upper arm plates, broadh' elliptical, though somewhat 

 pointed laterally, twice as wide as long (or nearly so), nearly or quite 

 in contact. Interbrachial spaces below covered by a very fine 

 scaling, markedly in contrast to that of the disk. Oral shield ovoid, 

 rather longer than wide, abruptly narrowed distally. Adoral plates 

 long, narrow within, where they meet, but very broad at outer end. 

 Oral papillae three on a side, the one at apex of jaw thick and rounded, 

 the second longer and pointed, the third smaller and rounded; be- 

 tween first and second, the scale of first oral tentacle pore may ap{)ear 

 like another papilla. Genital slits large, each bounded by a long 

 genital scale, the thickened 

 outer end of which is vis- 

 ible from above, just distal 

 to a radial shield; this thick- 

 ened end carries a peculiar, 

 slightly curved spine-like 

 outgrowth, which is some- 

 what flattened and bears 

 four or five digit-like proc- 

 esses at the tip (fig. 70, d). 

 First under arm plate very 

 small, squarish; succeeding 

 plates rounded pentagonal, 

 longer than wide, broadly 

 in contact. Side arm 

 plates, rather small, scarcely 

 meeting above, and not at 

 all below ; each plate carries 

 four slender, acute spines, 

 subequal (or the uppermost 

 and lowest, longest), about 

 equal to the joint. Ten- 

 tacle pores large, each with 

 two good-sized scales. Color (dried from alcohol), very light grayish. 



Localities. ^Albatross station 3713, off Ose Zaki, Honshu Island, 

 Japan, 45 to 48 fathoms, volcanic sand, shells, rocks, 1 specimen; 

 station 4815, Sea of Japan, lat. 38° 16' N. ; long. 138° 52' E., 70 fath- 

 oms, dark green sand, bottom temperature 51°, 1 specimen. 



2^/36.— Cat. No. 25530, U.S.X.M., from station 4815. 



It is hard to determine how much weight may be properly placed 

 on the peculiar digitate processes on the ends of the genital scales, as 

 a specific character. They are remarkably well developed in the 

 type but in the specimen from station 3713 they are much less 



Fig. 70.— AMI-HIODIA DIGITULA. X 8. a. FROM ABOVE; b, 

 FROM BEl.OW; C, SIDE VIEW OF THREE ARM JOINTS NEAR 

 disk; d, OUTGROWTHS ON UPPER END OF GENITAL SCALES, 

 GREATLY ENLARGED. 



