100 THE VOYAGE OF H.M.S. CHALLENGER. 



Upper latus having the shape of the sector of a circle, though when looked at accu- 

 rately, the basal and the carina! margins are seen to form an angle together, whence 

 the valve is quadrangular. Scutal and tergal margins almost of the same length. 



Rostrum very small, almost entirely hidden by membrane. 



Rostral latus broad, but very low. Scutal and basal margins almost parallel. 



Infra-median latus small, triangular ; umbo at the apex, which is slightly protube- 

 rant over the surface of the capitulum. 



Carina! latus of a very curious triangular shape. The umbo is protuberant beyond 

 the surface of the capitulum, and stands out also laterally beyond the surface of the carina. 

 The two carina! latera meet one another at the base of the carina. 



Length of the capitulum, IS "5 mm. 



Peduncle long (about as long as the capitulum), cylindrical, growing wider near 

 the capitulum. It is covered by membrane clothed with spines. The scales are totally 

 covered by this membrane, except in the lower part, near the attachment, where they 

 project over the surface. 



As this species is represented only by a single specimen, I have not studied its 

 internal structure. I have also failed to observe the complemental male. The species 

 inhabits the Pacific Ocean, near New Zealand, and was taken at Station 167, June 24, 

 1874 ; lat. 39° 32' S., long. 171° 48' E.; depth, 150 fathoms; bottom, grey ooze. 



Observations. — This species is very nearly related to Scalpellum velutinum, Scalpel- 

 lum eximium, Scalpellum gigas, Scalpellum darwinii, &c. Whereas all these species 

 were taken at very considerable depths, Scalpellum pedunculatum is an inhabitant of 

 rather shallow water. 



Scalpellum eximium, n. sp. (PL IV. figs. 6, 7 ; PL IX. fig. 10). 



Surface of the valves only partly covered by a chitinous and smooth membrane. 

 Valves fourteen. Carina simply bowed, with a very broad flat roof, and with the umbo at 

 the apex. Upper latus having the shape of the sector of a circle. Peduncle medium-sized, 

 with very strong scales. 



Of this splendid species only a single specimen was dredged; it belongs to the same 

 group as Scalpellum gigas, Scalpellum regium, Scalpellum darwinii, Scalpellum 

 velutinum, &c. 



The capitulum is very robust, and is only partly covered by a thin chitinous membrane. 

 There are slight interspaces between the different valves ; a little broader is the interspace 

 between the carina and the adjoining parts. 



The scutum is quadrilateral and convex. The length is not quite twice the breadth. 

 The umbo is at the apex, which slightly projects out of the occludent margin. From the 



