OPHIURANS OF THE PHILIPPINE AND ADJACENT WATERS. 107 



however, forming a continuous row. The length of the first ventral 

 spine equals that of the segment, and this length increases only very 

 slightly to the last dorsal spine, which does not exceed a segment 

 and a half. These spines are thick and strong with a very rugose 

 surface sometimes even showing small irregular and rather- well 

 spaced denticulations. As in 0. stultus the first ventral spine re- 

 tains the same character throughout the whole length of the arms 

 and does not show the least tendency to become transformed into a 

 hook in their distal portion (fig. 6). 



The tentacle scale is small and short, a little longer than broad, 

 with the tip rounded. 



The color of the two specimens in alcohol is white. 



A-ffinities and distinctive features. phiurothamnus excavatus 

 falls perfectly well within the genus Ophiurothamnus, with O. stul- 

 tus; it is easily distinguished from the latter by the very large and 

 very short spines of the dorsal surface of the disk, and by the 

 similarly rather short and thick arm spines. The strong depression 

 of the dorsal surface, corresponding to which is the very convex form 

 of the ventral surface, is seen in both the specimens at hand ; it may 

 be asked whether this feature occurs in the living animal, or whether 

 it is due simply to the action of the alcohol. 



OPHIOMITRA DIVES, new species. 



Plate 10, figs. 1-4 ; plate 94, fig. 2. 



Locality. Albatross station 5543; Tagolo Light bearing S. 75 W., 

 23.16 kilometers (12.5 miles) distant (lat. 8 47' 15" N., long. 123 

 35' 00" E.) ; 296 meters (162 fathoms) ; August 20, 1909; S. 



Two specimens (Cat. No. E. 22, U.S.N.M.). 



Description. The two individuals are in a very good state of 

 preservation, and the larger is quite complete. The diameter of the 

 disk is 17 mm., and the arms are about 110 mm. long; the arms are 

 rather thick, provided with strong spines, and the habitus of the ani- 

 mal is very robust. The second specimen is a little smaller, and its 

 disk is only 15 mm. in diameter. 



The disk is rounded and thick; the dorsal surface is gently de- 

 pressed in the middle, while the ventral surface is a little convex; 

 the borders are rounded. The dorsal surface between the large 

 radial shields is covered with small, imbricated plates becoming a 

 little larger at the periphery of the disk, in the interradial spaces and 

 in the vicinity of the radial shields. In the interradial spaces, there 

 may be counted four or five series of plates ; in the radial spaces be- 

 tween the two shields of each pair there is found only a single series 

 of narrow plates, and sometimes these plates do not reach the periph- 

 ery of the disk. Each plate carries a large rounded granule, which, 



