78 



H. M. S. "Siboga" collected this species at: 



Stat. 271. December 21, 1S99. Lat. 5°46'.7 S., Long. 134° o'E. Depth 1788 m. Bottom: bluish 

 green mud of uniform appearance. 



Observations. This species comes without doubt very near to Sc. compressuni, mihi, 

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

 characteristic of the "Challenger" species and are imperfectly calcified. 1 think it possible, 

 however, that these differences may turn out to be of less importance than we now think, if 

 we only had a richer material at our disposal. Sc. compressuni was collected in the Celebes Sea 

 at a depth of about 3900 m. 



10. Scalpelhmi javanicuin n. sp. PL VII, fig. 6, ba and 7. 



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

 Carina with the umbo at some distance from the apex and the part beneath the umbo very 

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

 the triano-le 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 

 different size, the largest of which has been figured. It is very nearly related to Sc. chitinosum, 

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

 species belongs Sc. hiflahim. 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 c a p i t u 1 u m 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- 

 quence 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. c/iitinoszcm. 



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

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

 is slio-htly produced and forms a very delicate but distinct beak which reaches to the base of 

 the tergum. 



The tergum has the calcified part V-shaped. Its occludent margin is very strongly 

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

 join the strong!)- 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 relation of the length 

 of the part above the umbo to the whole carina being about i to 7. The 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 of the sides are narrow. 



The upper latus would probably have a pentagonal shape if totally calcified. The 



