406 BULLETIN 100, UNITED STATES NATIONAL MUSEUM. 



OPHIOMUSIUM IMPOTENS, new species. 



Plate 90, figs. 9-11. 



Locality. — Albatross station 5605; Gulf of Tomini, Celebes; Do- 

 depo Island (W.) bearing N. 14° W., 10.93 kilometers (5.9 miles) 

 distant (lat. 0° 21' 33" N., long. 121° 34' 10" E.) ; 1,183 meters (647 

 fathoms) ; November 16, 1909. 



One specimen (Cat. No. 40920, U.S.N.M.). 



Description. — The specimen, unfortunately unique, has suffered an 

 accidental deformation, which was certainly antecedent to its cap- 

 ture, the result of which has been a modification in the form, the 

 arrangement, and the characters of the plates, principally on the 

 dorsal surface of the disk; it seems as if the individual had been 

 stretched in such a way as to elongate the disk in one direction and 

 and narrow it in another. But the characters on which a specific 

 distinction may be based do not appear to have been very much 

 altered, and the individual may be satisfactorily studied. I do not 

 know any species to which it may be referred, and I consider it 

 therefore as representing a new form. I believe that it should be 

 described in spite of the abnormal state of the single specimen. 



The disk is flattened ; it measures 9 mm. in diameter in the broader 

 part and 7 mm. in the narrower. The arms, which reach 20 mm. in 

 length, are slender, and they become extremely attenuated in their 

 terminal third. 



The dorsal surface of the disk is covered with plates of medium 

 size which are more or less imbricated and subequal. There may be 

 recognized a rounded dorso-central, a little larger than the neigh- 

 boring plates ; there must have been five primary radials transversely 

 broadened, and all a little larger than the other plates, separated 

 from the dorso-central by a row of smaller plates. The other plates 

 are arranged without any order. At the periphery of the disk and 

 in the middle of each interradial space a slightly larger plate may 

 be made out; in each radial space, at the level of the proximal angle 

 of the radial shields, there is also found a plate which is a little larger 

 than those around it. The radial shields are rather large, triangular, 

 half again as long as broad, and slightly divergent ; the two shields 

 of each pair are widely separated for their whole length by a single 

 row of plates in the distal portion, and by two or three plates in the 

 proximal portion. The radial shields do not appear to have pre- 

 served their normal form except on a single ray ; in two other radii 

 a single shield of each pair has the normal form, while its more or 

 less reduced fellow is shoved off to one side. In the two other radii 

 the plates which appear to represent the radial shields are very 

 small. 



