I I I 



The upper latus is trapeziform. The length of the carinal margin is less than half the 

 length of the scutal margin. The tergal margin has about the same length as the basal margin. 



The rostrum (fig. iu) is elongate, narrovv. It is almost entirely covered (especially 

 so in the specimen from Station 227) by the lateral parts of the rostral latera. 



The rostral latus is irregularly quadrangular. lts rostral margin is shorter than its 

 lateral margin, its basal margin much shorter than its scutal margin. 



The infra-median latus is triangular and has the umbo at the apex. The latter 

 does not quite reach to the slightly truncated scutal-basal angle of the upper latus. The height 

 of this small valve is slightly greater in the specimen from Station 241 than in that from 

 Station 227. 



The carinal latus has a pentagonal shape, with a short basal margin, a convex 

 lateral margin, and a straight upper margin. The umbo is below the middle of the carinal 

 margin, the two parts forming an angle together. The upper part is slightly hollowed out at 

 its base where the under extremity of the carina rests against it. 



All the valves are beautifully striated. The striae radiate, as a rule, from the umbo over 

 the surface of the valve. The ridges of growth are very indistinct; traces of them may be seen 

 on the scutum and the upper latus. 



The peduncle is short, cylindrical. The surface is covered by scales placed on a few 

 lono-itudinal rows. One of these rows on each side has more prominent scales and the number 

 of scales composing it is six or seven. The peduncle of the specimen from Stat. 241 was found 

 attached to a small piece of black stone (like lava) : the other specimen is attached to a small, 

 greyish, calcareous stone. 



Size. The total length of the specimen from Station 241 is 14,3 mm., the capitulum 

 alone measuring 11,3 mm. 



The two specimens representing this species were collected by H. M. S. "Siboga" at: 



Stat. 227. November 13, 1899. Lat. 4°5o'.s S., Long. i2/°59'E. Depth 20S1 m. Bottom: grey 

 mud with an upper layer of brown mud, both mixed with sand. 



Stat. 241. December 1, 1899. Lat. 4 24'. 3 S., Long. i29°49'.3 E. Depth 1570 m. Bottom: dark 

 sand with small stones. 



Observation. The two specimens differ from one another in that the rostrum is 

 much narrower in the one than in the other, as also that the shape of the tergum and the 

 size of the infra-median latus are not alike. But I consider the points of agreement of greater 

 importance than these differences. This new species comes nearest to Scalpellum vitreum collected 

 by the "Challenger" off Yeddo. 



33. Scalpellum hcxagonum n. sp. PI. VIII, fig. 12. 



Valves thirteen, not covered by membrane. Scutum nearly triangular. Carina simply, not 

 strongly bowed, umbo at the apex. Roof without ridges, laterally slightly convex. Upper latus 

 laro-e elono-ate hexaeonal. Rostral latus small : infra-median latus narrovv and very small ; carinal 

 latus rather large, with the umbo in the middle of the carinal margin. 



This new deep-sea species is represented by three specimens. 



