ii6 



The rostrum is hardly visible, being cov^ered on both sides by the margins of the 

 rostral latera. The rostral margins of the two rostral latera do not touch, so that a narrow 

 strip of the small rostrum remains uncovered. 



The rostral latus is quadrangular with the angle formed by the lateral and scutal 

 margins truncated. Its ba.sal margin is much shorter than the scutal margin. 



The infra- median latus is triangular, very narrow, with the umbo at the ape.\. 

 The apex does not quite reach to the truncated angle of the ujjper latus. 



The c a r i n a 1 latus is quadrangular, with the carinal margin only very slightly hollowed 

 out, with the upper margin straight and the basal margin slightly shorter than the lateral margin. 

 The umbo is very close to the lower e.Ytremity of the carinal margin and does not project 

 beyond the line of the carina. 



The peduncle is short, cylindrical but laterally compressed. The scales on the surface 

 are narrow, horizontally extended and at some distance from one another. They are arranged 

 in seven longitudinal rows: three on each side and one on the carinal side of the peduncle. 

 There are about 8 scales in each longitudinal row in the largest specimen. 



Size. The total length of the largest specimen was ii mm., that of its capitulum 8 mm. 



Both specimens were found attached to a brownish-coloured thread or fibre the nature 

 of which is unknown to me. 



They were collected by H. M. S. "Siboga" at: 



Stat. i6r. August 17, 1899. Lat. i°io'.5S., Long. 130° 9' E. Depth 798 m. Bottom: muddy 

 sand. 2 specimens. 



Observation. This species has a great resemblance to various other species, for 

 example, to Sc. gracile n. sp. It differs from it by the shape of the upper latus and of the 

 carinal latus, as also by the presence of a rudimentary rostrum of which no trace could be found 

 in Sc. gracile. But for the shape of the carinal latus it would be considered as belonging to 

 the same group of species as Sc. fonnosuiii, Sc. tnincatuni (which have a rostrum) and as 

 Sc. tenue, Sc. proclive and .SV. dcforine (species without a rostrumj. 



36. Scalpclhiin fissuui n. sp. PI. IX, fig. i and 2. 



Valves thirteen. Tergum with the apex recurved. Carina simply and not strongly bowed 

 with the umbo at the apex, with narrow sides and with a laterally convex roof, bordered by 

 ridges. Upper latus with a longitudinal fissure. Infra-median latus wine-glass shaped. Carinal 

 latus with the umbo at the base. 



The curious species is represented by four specimens, two large and two smaller ones. 



The capitulum is rather fiat and covered by a delicate membrane to which Radiola- 

 rians etc. adhere. Margins of the valves distinct. The occludent margin conve.x, in the smaller 

 specimens even more strongly bowed than the carinal margin. Apex of the tergum recurved. 

 Valves of the lower whorl well-developed. 



The scutum is quadrilateral with the occludent margin convex. The tergal margin is 

 also convex in the larger specimens ; in the smaller it is nearly straight. The lateral margin is 



116 



