lU) THE VOYAGE OF H.M.S. CHALLENGER. 



This species belongs to the same division of the genus as Scalpellwm japomcurn 

 and Scalpellwm insigne, the mosl characteristic feature of which consists in the 

 valves being imperfectl) calcified. The present species is represented by a single speci- 

 men only. 



The capitulurn has a nearly oval shape, and is rather flat. It consists of thirteen 

 valves, cadi of which is imperfectly calcified, and most of which consist of two segments 

 united at the place where the umbo is seated. The valves are clothed by membrane 

 which is covered with extremely minute and short spines. 



The scutum consists of an occludent and a tergal segment. The latter is narrow, 

 the former is of considerable breadth near the base, growing much narrower towards the 

 upper extremity. The basal margin forms an acute angle with the occludent margin, and 

 is hollowed out for the reception of the scutal margin of the rostral latus. The apex is 

 slightly recurved, the tergal margin slightly hollowed out. 



The tergum is triangular, and consists, its calcified part at least, of two segments of 

 about the same width and united at the apex, which is distinctly recurved. Occludent 

 margin arched. Carinal segment very long, reaching farther down than half the length 

 of the carina. 



Carina simply bowed, the flat roof is bordered on each side by a ridge. The umbo 

 is at a very short distance from the apex of the carina ; the part in front of it is a con- 

 tinuation of the sides of the valve. These are not very broad, and have the same breadth 

 over almost the whole length of the carina. Between the carinal margin of the tergum 

 and the side of the carina there is a rather broad oval interspace filled out with chitinous 

 membrane. 



Upper latus consisting of two segments which meet one another in the apex. This 

 penetrates into the cavity which was left between the two segments of the scutum. From 

 the umbo, which is seated at the apex, a third calcified segment starts, which, however, 

 is only small, and has a direction perpendicular to the carinal segment of the tergum. 



Rostral latus of irregular shape; a narrow segment runs along the basal margin of the 

 scutum ami penetrates into the hollow of this margin. A short and stout segment runs 

 close to the upper margin of the peduncle. 



Infra-median latus with the umbo near the base. A small triangular part beneath 

 the umbo ami a larger triangular part above it. The latter is hollowed out at the upper 

 margin for the reception of the scutal segment of the upper latus. This triangular part 

 is furnished on both sides with a rather prominent ridge. 



Carinal latus lias also the shape of a, V. The umbo is at the base, and at the foot of 

 the carina ; it is slightly protuberant beyond the carina, and is acutely pointed. The 

 carinal segment of the valve is rather long, the basal segment a little shorter. 



Length of the capitulurn, 22 - 5 mm. 



The peduncle is short, cylindrical (5 mm.). There are seven rows of scales, each con- 



