122 THE VOYAGE OF E.M.S. CHALLENGER. 



the upper margin is hollowed out. The umbo is seated al the upper extremity of the 

 carina] margin at the apex of the valve. The valve itself is divided by a ridge running 

 from the umbo to the hardly distincl angle formed by the lateral and basal margins. 



Length of the capitulum, 7 mm. 



Peduncle robust ; its length equals two-thirds of the length of the capitulum ; covered 

 by a very thick membrane. The scales are not very distinct. In the upper part of the 

 peduncle they stand close to one another, in the lower part, however, they are separated 

 by chitinous interspaces. Here they arc protuberant beyond the surface' of the peduncle. 



Of this' species I have not studied the structure of the animal contained within the 

 capitulum ; nor have I observed a complemental male at the place they ordinarily occupy. 



This species was taken at Station 192, September 26, 1874 ; lat. 5° 12' S., long 132 

 25' li: depth. 129 fathoms; bottom, mud. 



Observations. — This species, with regard to the structure of the valves and to the 

 smallness of the valves of the lower whorl, is nearly related to the large deep-sea species 

 Scalpellum, regium and others. It is distinguished from these species by the absence of 

 the rostrum. 



Scalpellum tritonis, n. sp. (PL V. figs. 9, 10; PL X. fig. 10). 



Valves covered by membrane, which is distinctly hairy. Valves thirteen. Carina 

 simply and not very strongly bowed, with the roof flat and the umbo at the apex. Upper 

 latus almost triangular, the carina! margin being very short. Valves of the lower whorl, 

 with the exception of the carina! latus, not much developed. Peduncle short. 



Together with some specimens of Scalpellum stroemii, this species was taken in the 

 Faroe Channel, by H.M.S. "Triton." Mr. Murray asked me to insert the description 

 of this species among those of the Challenger species. 



The capitulum,, though rather small, looks robust. Its shape is oval, a little 

 elongate, as the apex of the tergum is produced. The number of the valves is thir- 

 teen; scutum, tergum, carina, and upper latus are well-developed; on the contrary, 

 those of the lower whorl extremely small. The shape of the rostral latus resembles very 

 much the shape of the same valve in those species which have the carinal latus with the 

 umbo at the upper extremity of the carinal margin. The surface of the valves is covered 

 by membrane, which bears numerous small hairs. 



Thescutum is convex, quadrangular. The basal margin is the shortest, and is straight, 

 the occludent margin is arched, the tergal margin nearly straight, the lateral margin arched. 

 The area of the valve is smaller than that of the tergum. The umbo is at the apex, which 

 is slightly produced. 



The tergum is triangular, large. The occludent margin is only little shorter than the 

 occludent margin of the scutum ; it is arched, hence the apex is slightly recurved. The 



