Studies on marine Oslracods 227 



shorter than the three short bristles on the first endopodite joint (cf. below) and almost bare. 

 Exopodite: This has about the following proportions between the joints: 



I : II : III : IV : V : VI : VII : VIII : IX = 38 : 13 : 5 : 4 : 4 : 4 : 3 : 3 : 2. 

 In other words the first joint is about as long as the total length of all the following joints 

 and the length of the second joint is about as great as that of the three following ones together; 

 the lengths vary somewhat, however, though rather slightly. The bristle of the second joint 

 is about as long as the total length of the six or seven distal joints and has ventrally some 

 rather weak spines, which vary rather considerably in number (from about fifteen to twenty-five) 

 and dorsally, on the average, a rather smaller number of short, still weaker ones. The longest 

 natatory bristles are almost double the length of the whole exopodite and have rather broad 

 natatory hairs. The end joint has four bristles; of these the dorsal one is about as long as 

 the three or four distal joints, its hairs arc long but comparatively few in number. The 

 third to the ninth joints have basal spines of the same type as those found in C. (Vargxda) 

 norvegica, but they are, however, somewhat weaker. Endopodite (fig. 7) : The end joint 

 is sometimes not very well defined. The first joint has proximally a group of four bristles, three 

 of which are comparatively short; in addition this joint has at about the middle a single bristle, 

 somewhat longer than the longest proximal one and about as long as or somewhat longer than 

 the two distal joints of the endopodite; all the bristles of the first joint are sparsely furnished 

 with short and fine hairs. The second endopodite joint is quite without bristles. The bristle 

 of the end joint is about double the length of the endopodite and almost reaches the posterior 

 limit of the protopodite. 



Mandible (fig. 4): — Protopodite: The endite of the coxale has very 

 numerous spines; its two distal points are generally somewhat stronger and thicker than the 

 other spines, though only slightly so, and, contrary to the latter, are furnished with a few weak 

 secondary spines; between the two distal points a low point can sometimes be observed; cf. 

 above p. 182. Basale: The ventral side has seven bristles; two of them, the a-bristles, are 

 situated at the proximo-ventral corner; one of these is quite short, the other relatively long, 

 attaining about half the length of the ventral side of this joint; the b-bristle is very small; 

 somewhat proximally of the middle of the joint there are two c-bristles, one of which is not 

 quite as long as the longer of the two a-bristles, the other is exceedingly small, even very difficult 

 to distinguish; in addition there are two d-bristles, one of which is quite short, the other long, 

 of about the same length as the second endopodite joint; the last-mentioned bristle has along 

 a great part of its length very numerous rather long secondary bristles, only slightly arranged 

 in groups; the other bristles of the ventral side of this joint are furnished with short hairs or 

 naked. The proximal one of the three bristles of the dorsal side of this joint is situated somewhat 

 in front of the middle of the joint and is about half the length of the latter; the two distal 

 bristles are subequal and rather slightly longer than the proximal one; all three of them have 

 short fine hairs. The exopodite is rather considerably longer than the dorsal side of the 

 first endopodite joint. Of its two bristles, both furnished with short, fine hairs, the one situated 

 most distally is somewhat longer than this branch, the other is about twice as long as the first. 

 E n (1 o p o d i t e: Of the four ventr;d bristles on the first joint the two longest are somewhat 



