i;8 



is somewhat flattened laterally. The cariria reaches higher upward than the other valves. The 

 carino-lateral is narrow, the lateral broad, with the surface divided by longitudinal folds into 

 three parts. The colour is pink with red stripes, longitudinal and horizontal, all over the 

 surface. The orifice is rather large and somewhat toothed. The radii are rather broad, and have 

 oblique, slightly hollowed out, summits. They are of a light red colour, the alae being white 

 and having the summits straight. 



The structure of the compartments could not be investigated without destroying the 

 small specimen-, I presume the parietes to be with pores and the radii to be without pores. 



The se li turn (PI. XV, fig. 10, a and 5) is indistinctly furrowed, the growth-ridges being 

 only slightly prominent. The outer surface is not flat but feebly hollowed out in the middle 

 longitudinally. Internally, the articular ridge is not very elongated, but rather prominent. The pit 

 for the depressor muscle is well-developed as also is the cavity for the adductor muscle. No 

 tracé of an adductor ridge can be seen. 



The ter gum (PI. XV, fig. ior), has the apex blunt, the scutal margin straight, the 

 basal margin distinctly hollowed out, and the carinal margin slightly convex. There is no 

 longitudinal furrow, but a shallow longitudinal depression parallel to the scutal margin. The 

 spur is separated from the basi-scutal angle by a distinct excavation, and the posterior margin 

 of the spur slopes into the basal margin ; spur bluntly pointed at the extremity. 



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



Mouth: labrum (PI. XV, fig. 11) has a rather deep notch, and the lateral parts 

 rather short. On each side of notch three stout, triangular, pointed teeth are seen. 



Pal pi (PI. XV, fig. 11) of oval shape, not elongated, only one and a third times as 

 long as broad. The hairs on the outer surface are not disposed in a row, but form a somewhat 

 irregular group near the free extremity of the palpus. They clo not reach farther over the outer 

 surface than half way its length. No groups of short hairs along inferior margin. The inner 

 surface is furnished with very numerous hairs, which are partly recurved. 



Mandible (PI. XV, fig. 12), has the first tooth sharp, and the distance between 

 the extremities of teeth 1 and 2 greater than that between 2 and 3. Third tooth doublé, fourth 

 small, but also doublé, fifth very small and the inferior angle rudimentary. 



Maxilla (PI. XV, fig. 13) of triangular shape, with a notch behind the two upper 

 spines, three spines on the middle part, and two strong spines on a slightly elevated part near 

 the inferior extremity of the edge. The length of the middle spines about three quarters of the 

 length of the spines of the upper pair. 



Outer maxillae (PI. XV, fig. 14) have the outer lobe not very elongated, and with 

 a rather broad basis ; the outer margin is strongly convex, the inner margin nearly straight, 

 the free extremity somewhat pointed. A distinct row of spines extends over the outer lobe, 

 directed towards the rounded inner lobe. 



Cirri. First pair has very unequal rami of 5 and 12 segments. 



Second pair has the rami nearly equal, of 6 to 7, and 7 to 8 segments; each seg- 

 ment slightly protuberant only on its inner face. 



Third pair slightly longer than the 2 nd pair, number of segments 7 to 8, and 8 to 9, 



