7<; THE VOYAGE OF II. M.S. CHALLENGER. 



swollen, and probably functions as a receptaculum seminis (r.s.). I think I have observed 

 an opening uear <>., but I do not feel quite sure. 



Scalpellum carinatum, n. sp. (PL III. figs. 7, 8). 



Valves fourteen; surface smooth; valves separated by broad chitinous interspaces. 

 Carina bowed, with a flat roof, the apex of which, however, is not the apex of the valve 

 which, therefore, is angularly bent. Upper latus of an irregular pentagonal shape. Infra- 

 median latus large and wine-glass-shaped. 



Tins species has about the same shape of carina as Scalpellum japonicum and 

 Scalpellum recurvirostrvm. This form stands between the carina with a perfectly flat 

 roof (e.g., Scalpellum robustum), and those with a distinct angularly bent carina (e.g., 

 Scalpellum cuhjarc). The species is represented by two specimens, only one of which, 

 however, is full-grown. 



The capitulurn consists of fourteen valves, and is covered by a very thin, transparent 

 chitinous membrane. The valves are separated by distinct interspaces of membrane. 

 The capitulurn is coloured dirty white, the interspaces have a yellowish-grey colour. 



Scutum elongated, twice and a half as long as broad ; apex pointed, basal margin 

 oblique, forming a right angle with the occludent margin, but passing with a rounded 

 angle into the lateral margin. This margin is slightly hollowed out, and is separated from 

 the tergal margin by a not very large rectangular projection or shoulder. The occludent 

 margin is very convex, the tergal margin is short and hollowed out. The umbo is at the 

 uppermost point, where the valve shows a distinct triangular and feebly recurved projection. 



Tergum large, triangular, flat, with the inferior part produced and the apex much 

 recurved. The scutal margin has a small projection near the occludent margin, and this 

 projection is placed behind the triangular projection at the apex of the scutum. The 

 occludent margin is very much arched, the carina! margin is divided by a small projection 

 near the apex into a small superior and a long inferior part, both parts being concave. 



The carina in the inferior part is simply bowed, with a flat roof, much increasing in 

 width from the upper to the lower end, and bordered on each side by a not very distinct 

 ridge. The umbo is seated at the top of the flat roof and at a small distance from the 

 apex of the valve. The part above the umbo is formed by the upward prolongation of the 

 sides of the valve, which diminishes in size below, so as to terminate in a long point at 

 the base of the carina. 



The upper latus is irregularly pentagonal, flat ; upper half acuminate, lying between 

 the tergum and the scutum, the lower half broad. The umbo is not at, but near, the 

 apex ; the valve therefore is added to not only downwards but also a little round the two 

 sides of the apex. These additions do not take place in the early stages of growth, and 

 therefore, they form a depressed rim. 



