282 rvc.i; sivousitiiuu 



Drscripliou : V >' m a If: 



Slioll: - l.ciiuth. (>,3 — 6,8 nun. LtMijitli : liciulil. al>mil 1,.")5:1; length : breadth, 

 about '_M : 1. Seen Ironi the side (fiu;. 1) it is mndciati'ly elongated with its greatest 

 lieiiiht somewhat in front of the middle and the anterior part soniewliat largei' than the posterior 

 one. The dorsal margin is rather strongly arched, either uniformly or often somewhat flattened 

 at the middle, joining the anterior and the posterior margins without any indication of corners. 

 The ventral margin is uniformly arched with a rather decided bulge anteriorly, somewhat more 

 stronglv archeil at this part than the dorsal margin; joining witliout any sign of a corner the 

 posterior margin, together with which it forms a slightly convex, straight, or sometimes even 

 a very slightly concave line. The posterior part of tlie shell is drawn out into a sharply projecting, 

 acute angled, but well rounded corner at or a little below half the iieiglit of the shell. The 

 rostrum has a rather strongly projecting but broadly rounded anterior corner; its ventral corner 

 is rather pointed. Seen from the side the rostral incisur is often of rather a varying type, the 

 variations being obviously caused by the flexibility of the shell; yet it was not found to be so 

 deep as it is shown in pi. V, fig. 1, G. W. MOLLER, 1906 a. Seen from above (fig. 2), 

 the shell is broadly lentiform with its greatest width a little in front of the middle and with 

 uniformlv curved side contours, which are, however, somewhat concave in front of the lateral 

 eyes. The front and back ends are rather well pointed. The surface of the shell 

 is quite smooth without any sculpture and quite without bristles. The pores of the surface 

 are difficult to observe with certainty. Seen from within (fig. 3): Medial bristles: 

 Near the ventral point of the rostrum there is a verruciform swelling, projecting rather strongly 

 and directed inwards and downwards; it is furnished along the anterior side with a dense row 

 of about 15 to 20 rather long and powerful and smooth bristles. Basally on this swelling there 

 is a single tube-like bristle, thick but evidently very flexible; in some rare cases two of these 

 were present. Dorsally of this swelling there is a row of bristles running upwards, of the same 

 type as the first-mentioned bristles: the number of bristles in this row varies, from six to as 

 many as sixteen have been observed. Apart from these just mentioned the rostrum is usually 

 quite without medial bristles, but sometimes, however, one or a few short, scattered bristles 

 may be found. The two bristles close to the inner margin of the incisur are of about the same 

 type and size as the bristles in the row mentioned above. Above them, about half-way between 

 the joining line and the margin of the shell or somewhat nearer the latter, there is a single bristle, 

 quite short and rather weak. Besides these three bristles a few other short bristles are sometimes 

 found inside the incisur. The list is usually quite without bristles along the whole ventral side 

 of the shell even just behind the rostral incisur, where, in most forms of this family — in all that 

 are described in this work — bristles are to be found. Posteriorly it has, however, a few bristles. 

 The posterior part of the list, which is somewhat broader than the anterior one, is also 

 characterized by pore-like formations, such as are reproduced on p. 228 of this work for 

 C. (Doloria) levis, but I believe I have ascertained with certainty, with Reichert's ocular 4, 

 Leitz' i m mers. yi2,*that these do not end in a short bristle. (The list appears on the whole 

 to be very like the one described for the species just mentioned, but has, however, still fewer 

 bristles than this.) On the part between the list and the ventral and posterior margins of the 



