178 
is somewhat flattened laterally. The carina 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 scutum (Pl. XV, fig. 10, a and 4) 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 
trace of an adductor ridge can be seen. 
The tergum (Pl. XV, fig. roc), 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 (Pl. 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. 
Palpi (Pl. 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 do 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 (Pl. 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 double, fourth 
small, but also double, fifth very small and the inferior angle rudimentary. 
Maxilla (Pl. 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 (Pl. 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™¢ pair, number of segments 7 to 8, and 8 to 9, 
5° 
