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



The carinal lotus, is large and nearly pentagonal. Three of the margins are of about 

 the same length ; l he basal margin describes a very obtuse angle with the lateral margin ; 

 the lateral margin forms nearly a right angle with the upper margin ; the carinal margin is 

 twice as long as one of the other margins; it is divided into two portions, the superior 

 one is slightly hollowed out, the inferior one is slightly arched, and meets that of the valve 

 of the other side at its under extremity. The umbo is placed at the angle which the 

 two portions of the carinal margin describe together. 



Length of the capitulum of the largest specimen not quite 7 mm. 



Peduncle very short, totally covered by calcareous scales. These have very promi- 

 nent edges, and are placed in eight longitudinal rows, each of them consisting of only 

 five scales. 



This species was taken October 17, 1873, off Nightingale Island, at a depth of 100 

 fathoms (Station 135, Island of Tristan da Cunha ; bottom, rock, shells). 



Scalpellum hirsutum, n. sp. (PI. IV. fig. 19). 



Valves fourteen, covered by membrane, clothed with very long hairs. Carina simply 

 bowed, umbo at the apex, roof Hat. Valves of the lower whorl small. Upper latus 

 triangular. Eostrum represented by a very narrow stripe which is distinctly visible at 

 the surface. 



This small species is represented by a single specimen only. 



The capitulum is characterised by the long hairs which clothe the membrane covering 

 the valves. The valves of the lower whorl are rather small, the other valves — and es- 

 pecially the scutum and the tergum — are elongate, with produced apices. 



The scutum is elongate, convex; more than twice as long as broad, with the upper 

 part produced and pointed. The pointed extremity is slightly protuberant beyond the 

 occludent margin of the tergum. 



The tergum is large, elongate rhomboid. The umbo is at the apex, which is con- 

 siderably produced. 



The carina is simply bowed, and has a Hat roof, much increasing in width from the 

 upper to the lower extremity. Its sides are not much developed. 



The upper latus is almost triangular, with the carinal-basal margin arched. The 

 apex is slightly produced and is totally enclosed between the scutum and tergum. 



The rest rum is small, linear-shaped ; enclosed between the rostral margins of the 

 rostral latera. 



The rostral latus is quadrangular, basal and scutal margins parallel. 



The infra-median latus is triangular; umbo at the upper extremity. 



The carinal hit us is of an irregular shape, with the umbo near the upper extremity. 



