284 , TACK SKOdSHKRG 



shell there are a few short bristles to be observed, especially posteriorly near the margin of the 

 shell; similar bristles may also sometimes be found inside the list. The selvage (figs. 4, 5, 6) is 

 rather wide on the rostrum and has exceedingly fine and close cross-striation at this part — 

 this striation could only be indicated quite rovighly in the accompanying figure. This part of 

 the selvage is sometimes divided into rectangular divisions varying in width; its edge is exceed- 

 ingly finelv serrated at this part. Along the anterior edge of the incisur the selvage has a 

 structure like that shown in fig. 4. in other words it is divided into rather wide, conical parts, 

 which are rather strongly c-hitinized; these cones at the edge produce an evident undulation; 

 in addition an exceedingly fine striation can be traced here. Close to the two medial bristles 

 at the inner margin of the incisur the selvage suddenly comes to an end. It is widest along the 

 posterior edge of the incisur, and becomes narrower and narrower posteriorly, suddenly stopping 

 on the ventral side of the shell about five sixths of the way along the shell. Along the posterior 

 edge of the incisur the selvage is divided similarly into conical parts, rather strongly chitinized, 

 bat these cones arc, however, considerably narrover than those which characterize the selvage 

 on the anterior edge of the incisur; at the free edge of the selvage these conical parts continue 

 as powerful, free points. Besides the cones the selvage is also characterized here by a close 

 and exceedingly fine cross-striation; posteriorly the conical structures gradually disappear 

 altogether and only the fine cross-striation is to be found, even the latter often only with diffi- 

 culty; (this fine striation is only partly and very roughly indicated in the accompanying figure). 

 Along the ventral side of the shell the edge of the selvage is closely and fairly finely serrated 

 (see fig. 6). Just behind a point half-way along the shell a rather wide secondary selvage with 

 very coarsely serrated edge (cf. fig. 6) issues basally on the inside of the selvage; it stops at 

 a point somewhat in front of the posterior boundary of the selvage. The specimens examined 

 by me (preserved in 85 % spirit) had leather-like shells, apparently quite without any calciferous 

 incrustation. They are of a dark-brown colour and semi-transparent; outside the lateral 

 eyes, however, the colour is ahiiost completely absent on an almost circular part with a diameter 

 of about a third of the length of the shell. (The boundary of this circle is indicated diagrammatic- 

 ally on the figure by means of a line; the transition from the pigmented to the unpigmented 

 part is, however, gradual.) 



First antenna (fig. 7): — The anterior bristle of the third joint, fixed somewhat 

 proxinially of the middle of the joint, the postero-distal bristle of this joint, the two bristles 

 of the fom-th joint, the bristle of the sixtli joint and the a-bristle of the seventh joint are all 

 comparatively weak, subequal, short, of about the length shown in the figure mentioned; their 

 length varies, however, to some extent, though only very slightly; they all have short, fine hairs. 

 'J'he sensory bristle of the fifth joint is somewhat longer than the anterior side of the second and 

 tliird joints. Of its thirteen sensory filaments the nine proximal ones are rather thick — of 

 al)out the same thickness tliroughout — and long, being about a thiixl of the whole length of 

 the bristle. The three folhnving filaments, situated at a considerable distance from the former 

 ones, are much shorter and finer; their position relative to each other varies to some extent; 

 sometimes they are scattered and sometimes situated very close together. The remaining one, 

 situated at rather a long distance from the point, is exceedingly short. Of the bristles on the 



