7 S 



H. M. S - oll< cted ihis sp ,t 



Stat. 271. Dcccmbei 21, Long. 1 34 o' 1 Depth 1788 m Bottom: bluish 



. 11 mud "i unifoi m appearai 



(i itions, rhis species comes without doubt very near to Sc. compressum, mihi, 



the main difference being that the scutum and tergum do not show the prominent ridge 



teristic of the "Challenger" species and are imperfectl) calcified. I think it possible, 

 however, that these differences may turn out to I"- of less importance than we now think. it 

 we '>nl\ had .1 richer material at our disposal. Sc. compressum was collected in the Celebes Sea 



depth of about 391 10 in. 



10. Scalpellum javanicum n. sp. PI. VII, fig. ". '></ and 7. 



Valves thirteen, partly calcified, covered by chitinous membrane. Tergum strongly recurved. 

 rina with the umbo al some distance from the apex and the part beneath tin- umbo ver) 

 ily bent. Calcified part of the upper latus of an irregular triangular shape with the base of 

 the triangle hollowed out. Calcified part of the infra-median latus wine-glass shaped. Carinal 



latus with the umbo at the base. Rostrum absent. 



This species is represented in the collection of the "Siboga" by three specimens of 

 differenl si/e. the largesl of which has been figured. It is very nearly related to Sc. chitinosum, 

 and to Sc. japonicuw, mihi, the latter collected by the "Challenger". To the same group of 

 species belongs Sc. inflatum. I describe them as so many different species though admitting 

 the possibility that two or even more of them may afterwards turn out to represent different 

 forms or varieties of the same species 



The capilulum of the present form has the occludent side more strongly arched than 

 the carinal. It is rather broad, being only one and a half times as long as broad. In conse- 

 (|uence of the roof of the carina being of considerable breadth near the base, the capitulum is 

 thick in the undermost part by no means so flat as that of Sc. chitinosum. 



The scutum much resembles the same valve of Sc. chitinosum. The tergal segment 

 of the present species, however. is much shorter than in the other. The apex ol the scutum 

 is slightly produced and forms a very delicate but distinct beak which reaches to the base ol 

 the tergum. 



The tergum has the calcified part V-shaped. lts occludenl margin is very stronglj 

 arched; the carinal margin of the calcified part is distinctly hollowed out; where the two margins 

 join the strongly recurved apex is formed. The surface occupied by the tergum in this species 

 is smaller than the corresponding surface in Sc. chitinosum. 



The carina has the umbo at some distance from the apex: the relatioii ol the length 



the part above the umbo to the whole carina being about 1 to -. 1 he part underneath 



the umbo is only feebly bowed and has a roof and narrow sides. The roof grows rather broad 



towards the base and is nearly quite flat: the ridges so distinct in many other species being 



but very feebly indicated. The calcified parts ol the sides are narrow. 



upper latus would probablj have a pentagonal shape if totall) calcified. The 



