,:ilui>i n. sp. PI. VIII, !i. | .nul |</. 



Valves i | not covered by membrane. Carina simply bowed with a flat rooi', bordered 



listinct ridges. Upper latus pentagonal with the umbo al tin- apex; apex produced. Rostrum 



narrow, slightly broader .it the upper extremity. Infra median latus irregularly wine-glass shaped, 



with the umbo near the base. Carinal latus with the umbo nol far from the l>ase. Peduncle 



. short 



rhis species is represented bj one specimen only. 



rhe capitulum is il.n, broadest about the middle of the scutum, slightlj narrower 



towards the luis.-, distinctly pointed towards tin- upper extremity. The carina is not strongly 



• 1. so that the whole capitulum looks ;is il" slightly recurved. No membrane covers the valves. 



rhe se 11 tu m li. is the ordinary shape; its occludent margin is strongly arched. It is 



about twice as long as broad. I'lu- apex is slightly produced and overlaps the tergum. 



The tergum is rather large; the occludent margin is nearly straight, tin- scutal margin 

 also straight, tin- carinal margin slightly convex beneath and slightly concave above the middle. 

 rhe apex <>( the carina presses very slightly into the carinal margin of the tergum. Apex 

 hardly produced. Growth lines visible, luit not ver) distinct. 



TIn- carina has a distinct roof and well-developed sides. The roof grows broader from 

 the apex to the base, tin- sides are broadest in tin- upper part. The umbo is at the apex. The 

 is flat, bordered 1>\ distinct ridges. 



The upper latus is pentagonal, with the scutal and tergal margins by far the longest. 

 The umbo is at the apex which is distinctly produced. The growth ridges are visible on this 

 vake more distinctly than on any of the others. 



The rostrum (fig. 4</ is very narrow. slightly broader towards the upper extremity. 

 It does not reach quite so far downwards as the basal margin of the rostral latus. 



The rostral latus is quadrilateral. lts lateral margin is convex, its scutal margin 

 slightly hollowed out. The umbo is at the angle of the rostral and scutal margins. 



The infra-median latus lias the shape of a wine-glass, more or less inclined to 

 one side. Though the name I propose for the species was chosen from this characteristic, I do 

 not consider the shape of this valve of so essential importance: I aftcrwards discovered that 

 the right infra-median latus shows by no means the same shape so distinctly as the left. 



The carinal latus is rather large with a long carinal margin and the umbo seated 

 near the base. The lateral margin which is sinuous in the valve of the left side, describes a 

 nearly re^ular curvature in the same valve of the right side of the capitulum. 



The peduncle is very short, the scales are relatively large and not numerous; they 

 er the whole surface and are much pressed together. 



Si ze. The total length of the specimen is 6,6 mm., that of the capitulum 5.,} mm. 



["hè "Siboga" collected the single specimen at: 



Stat. 300. January 30, 1900. Lat. 10 48'.6 S., Long. 123 23'.] E. Depth 918 m. Bottom: fine 



v mud. 



Observation. This curious deep-sea pecies may bc easily distinguished from tin- 



