.^18 TAGE SKOGSBERG 



is smooth, practically entirely without bristles. Seen from inside: The medial bristles 

 are about the same as in the type species. On the rostrum there are from seven to eleven bristles, 

 simple or weakly bifurcated; the ventral ones of the series are not fixed on a Verruciform swelling. 

 Inside the incisur there is, apart from the two bristles that are situated close together near 

 its inner edge, generally only a short, simple bristle near the joining line. The bristles on the 

 list are most frequently simple; they decrease in number towards the back and seem to disappear 

 entirely along the posterior part of the ventral margin. All the medial bristles are quite or 

 almost quite bare. The spines along the list inside the posterior margin of the shell are almost 

 the same as those of the type species. On the right valve they are large, decreasing rather 

 slightly in size ventrally and varying somewhat in number, from fifteen to eighteen; of these 

 the two ventral ones were very small in one case, in two cases only the most ventral one was very 

 small. On the left valve the spines are very small and difficult to verify, some of them even seem 

 to be missing. That part of the list which has spines has, in addition, a few — in most cases 

 about one or two for each spine — short and exceedingly fine bristles. The part between the 

 list and the margin of the shell is of about the same type as in the type species. The selvage is 

 rather wide along the anterior margin of tlie rostrum, but is narrow along the posterior rostral 

 margin; along the posterior margin of the rostral incisur it is very wide, filling the whole incisur; 

 it continues along the whole ventral margin of the shell, extending rather considerably beyond 

 the latter except at one part just in front of the middle, where it is rather narrow.* At the last- 

 mentioned part it is characterized by the fact that its edge is closely and finely serrated, the 

 edge of the remaining part is almost even. In the incisur the selvage is rather strongly cross- 

 striated, at the remaining part the cross-striation is exceedingly fine. 



First antenna (fig. 4): — This has seven joints; the fifth and sixth joints are 

 practically entirely joined (the original boundary, shown in the accompanying figure, can only 

 be verified with difficulty). The approximate projDortions between the joints are: 



I^; 11^; III^; IV ^; (V ^; VI |); VII |; VIII 0,5. 



Third joint: The bristle on the anterior side is fixed at about the middle of the joint and is 

 about half as long as the anterior side of this joint. The posterior distal bristle is nearly as long 

 ■ as the total length of the posterior sides of the two following joints or else a little shorter. The 

 anterior bristle of the fourth joint is quite short, scarcely half the length of the anterior side 

 of this joint, the posterior one is somewhat longer, about as long as the posterior side of this 

 joint. The sensory bristle of the fifth joint is somewhat longer than the anterior side of the second 

 joint. It has eleven bare sensory filaments, situated in about the positions indicated in the 

 accompanying figure; the eight proximal ones are somewhat thick in proportion to the distal 

 ones, and are relatively long, being about a third to a half of the whole length of the bristle; 

 the two following filaments are narrow and only about a fifth of the length of the bristle; the 

 distal one is very short, almost verruciform. The bristle of the original sixtli joint and the 

 a-bristle of the original seventh joint are subequal, rather short, being only about as long as the 

 original sixth joint. These bristles, like those of the third and fourth joints, have short, fine 



This is not shown in tin' drawiiit,'; in this specimou tlie selvagu was direclt'd somewhat inward. 



