612 TAGR SKOGSBERG 



laterally, there are usually five (in exceptional cases four or six) bristles, of somewhat different 

 lengths, the longest being in most cases as long as or somewhat longer or shorter than the proximal 

 height of this joint, the shortest in most cases about half as long. These bristles are most 

 frequently well pointed and either have short hairs or else a larger or smaller number of them 

 are furnished with rather long hairs at the middle; the latter character varies a good deal, often 

 even within the species. In exceptional cases this joint may have no bristles at all. The second 

 joint has ventrally, at or somewhat distally of the middle, a single short-haired bristle, in most 

 cases of the tube-bristle type and most frequently about half as long as the height of this joint 

 or still shorter. In exceptional cases it may be almost entirely reduced. The two bristles of 

 the third joint are in most cases of about the same length and type as that of the preceding joint. 

 In exceptional cases the ventral one of them may be almost completely reduced or even quite 

 absent. The three bristles of the end joint are usually subequal and about as long as the exopodite. 

 All of them are usually furnished with rather long and powerful natatory hairs along the distal 

 two-thirds of their length; in exceptional cases the ventral one has short hairs. It ought perhaps 

 to be specially pointed out that these bristles are not modified distally as sensory organs. This 

 limb is in most cases quite bare. The fig. 29 of C. symmetrica given by me below agrees fairly 

 well with the ,, normal type" described here. 



F e m a 1 e: — This is rather considerably smaller and weaker than that of the male; 

 the musculature especially is considerably less strongly developed. In order to show the relative 

 sizes it may be pointed out here as an example that whereas the exopodite of this limb (excluding, 

 of course, the end bristles) is about 1,5 mm. long in males of C. symmetrica 4,0 — 4,1 mm. long, 

 this branch measures only 1,0 — 1,1 mm. in females of the same species whose shells are 4,3 to 

 4,5 mm. long. Apart from this fact this limb differs from that of the male chiefly in the bristles 

 of the exopodite. These are developed in the foUowing way: First joint: The dorso-distal bristle 

 has, as in the male, short hairs, and is in most cases about as long as or somewhat shorter than 

 half the length of this joint. There are five bristles ventraUy on this joint; two of these are situated 

 at or somewhat proximally of half the length of this joint, one somewhat medially, the other 

 somewhat laterally, the three remaining ones are near the distal boundary of this joint. These five 

 bristles, like the single bristle situated laterally, somewhat dorso-distally of the middle of this 

 joint, are better developed than in the male, in most cases subequal, about as long as or somewhat 

 shorter than this joint and are all often furnished with rather long hairs at the middle 

 and short hairs distally. Both the two bristles of the endopodite and these last-mentioned six 

 bristles are most frequently well pointed, the short dorso-distal bristle is in most cases of the 

 tube-bristle type, the latter sometimes with a rather long end hair (as in my fig. 26 of C. sym- 

 metrica). The bristles of the second and third joints are most frequently subequal and somewhat 

 shorter than the second joint; they have short hairs and are in most cases of the tube-bristle 

 type. The three bristles of the end joint are in most cases of about the same type and length 

 as the corresponding bristles on the fifth limb but they are all in most cases somewhat longer 

 comparatively. The middle one is most frequently about one and a half times as long as the second 

 exopodite joint or somewhat longer. The fig. 30 of C. symmetrica given by me below agrees 

 fairly well with the ,, normal type" described here. 



