190 BULLETIN 100, UNITED STATES NATIONAL MUSEUM. 



OPHIACTIS MACULOSA Martens. 



Plate 63, figs. 6, 7. 



Ophiactis maculosa MARTENS ('70), p. 248. LYMAN ('82), p. 122. H. L. 

 CLAKK ('15), p. 263, pi. 11, figs. 3, 4. 



Locality. Albatross station 5136; vicinity of Jolo; Jolo Light 

 bearing S. 37 E., 1.30 kilometers (0.7 mile) distant (lat. 6 04' 

 20" N., long. 120 59' 20" E.) ; 40 meters (22 fathoms) ; Feb- 

 ruary 14, 1908 ; S., Sh. 



One specimen (Cat. No. 41051, U.S.N.M.). 



Notes. This individual is not in good condition; some of the 

 plates of the dorsal surface of the disk are torn away, and the arms 

 are incomplete, broken off at a certain distance from the base. It 

 can be seen nevertheless that it agrees well with the two photographs 

 which H. L. Clark has published of this species ('15, pi. 11, figs. 3, 4). 

 Martens' description, which is altogether vague and insufficient, can 

 not be relied upon, so I have thought it advisable to give here some 

 notes relative to the Albatross specimen, which is unfortunately not 

 in a satisfactory state of preservation, at the same time regretting 

 that H. L. Clark has not described the one from the Philippines 

 which he has photographed and which appears to be very well pre- 

 served. 



The disk must be 5 mm. in diameter, and the arms might reach 30 

 mm. in length. The disk appears slightly excavated in the inter- 

 radial spaces. Its dorsal surface is covered with rather large, un- 

 equal plates, larger in the central region and becoming smaller 

 toward the periphery. I can not recognize any primary plates in 

 my specimen ; in H. L. Clark's photograph there seems to be a circlet 

 of five large in terra dial plates. The plates are not imbricated in the 

 central region of the disk, and they are here without spines. Only 

 the peripheral plates, which are very much smaller than the others, 

 bear a few spines and these are small, short, and conical with the 

 point blunted. These spines are found on the plates of the ventral 

 surface of the disk, but these plates do not cover the whole of this 

 surface, and are found only in a triangular area of which the apex 

 is at some distance from the mouth shields, and which does not reach 

 the genital slits. The radial shields, which are of medium size, are 

 triangular, with the external side convex and the apex proximal; 

 they are two and a half times as long as broad, and their length 

 exceeds half the radius of the disk. The two shields of each pair are 

 only slightly separated ; they are in contact distally by their external 

 angle or even for a small part of their length, and are separated 

 inwardly by a series of plates. 



The outlines of the mouth plates, which are not very evident in 

 H. L. Clark's photograph, show very clearly in my specimen. The 



