200 



in varying degrec, coloured orange. Shell light-reddish, partly white, with vertical red stripes. 

 Surface of compartments furrowed. Scutum with the apex sharply pointed, articular ridge not 

 prominent, adductor ridge hardly visible. Tergum with a prominent articular ridge and a broad 

 spur with rounded extremity. Labrum with three teeth on each side of notch ; palpi with ciliae 

 in groups along inferior margin. 



The specimens are covered by a sponge-like coat. The shape of the shell is conical, 

 in younger specimens more globular. All have the orifice rather large (PI. XIX, flg. 8), the 

 radii broad, with their summits oblique, slightly oblique, or even, in one of the specimens, 

 quite parallel to the basis: the summits of the alae are rounded. The colour of the shell is 

 dirty-white, striped longitudinally and spotted here and there with red ; the rostrum is in most 

 specimens almost perfectly white. The radii are more or less distinctly orange-coloured. The 

 compartments and the radii have no pores. In the lower part of the shell longitudinal ridges 

 are found on the interior surface; these touch each other at several places and also close to 

 the basis, which causes a transverse section to sometimes look as if pores were present. The 

 basis has no pores; the longitudinal ribs of the inner surface of the shell can be foliowed on 

 the basis, where they radiate from the centre. 



The scutum (Fig. 9, a and c) is of a regular triangular shape, with the tergal margin 

 as long as the basal margin, or even slightly longer; it is pointed towards the apex. Occludent margin 

 indistinctly toothed, basal margin not strongly convex. Lines of growth rather numerous, not 

 very prominent. Surface indistinctly striated longitudinally. On the inner surface, the articular ridge 

 not prominent, sloping towards basi-tergal angle; adductor ridge hardly to be distinguished, 

 represented by a slight uplifting only of the internal surface. A small and shallow pit for the 

 lateral depressor muscle and an indication only of the cavity for the adductor muscle. 



The tergum (Fig. 9, ö and d) has the apex not produced; the carinal margin is rounded, 

 the scutal margin straight. The longitudinal furrow is represented by a slight depression, the spur is 

 situated at a little distance from the basi-scutal angle ; it is not very long and its width, measured 

 at the height of the basal margin, is about two -fifths of the length of that margin. lts lower end 

 is rounded; the basal margin makes an angle with the posterior margin of the spur. The articular 

 ridge is prominent and the crests for the depressores are well-developed. On the inner surface 

 a triangular part of the surface situated at the apex of the valve, is distinctly striated transversely. 



With regard to the structure of the animal's body the following may be said : 



Mouth. Labrum (PI. XIX, fig. 10). Notch wide at entrance, three teeth on each side. 

 In the specimen from Stat. 299 one tooth is situated half way along the margin of the notch, and 

 one tooth is wanting at one side. Delicate hairs disposed along notch and between teeth 1 and 2. 



Pal pus: broad, stout, somewhat quadrangular, with the superior margin nearly straight 

 and the inferior one arched. Hairs along superior margin numerous, but situated at some distance 

 from each other. They combine near free extremity with the very numerous and longer hairs 

 disposed on distal part of outer surface. A relatively large part of outer surface is covered with 

 hairs. The inner surface bears a longitudinal group of shorter and curled hairs situated close 

 together, the same sort of hairs being also seen on the part of the inner surface between that 



