studies on marine Oslracods 'ol 



ends and weakly irregularly curved sides. The surface of the shell, hinge of the shell, selvage 

 and lamellae of the shell are similar to those of the male. 



First antenna (fig. 13): — The boundaries between the original first and second, second 

 and third, and third and fourth joints are developed rather distinctly, and, at least sometimes, 

 traces of the boundary between the original fourth and fifth joints can be found. The bristles 

 on the original fo'irth joint are almost as long as the total length of the three ]>roximal joints 

 (only slightly shorter than in the male); the number found was 21 — 23. The original fifth joint 

 has four bristles of different lengths; the longest one is in most cases somewhat shorter than the 

 sensory bristles of the fourth joint, the shortest is about a third of the length of the longest one; 

 there are sometimes a few short hairs distally on the longest one, the others are most frequently 

 bare; the longest one is perhaps somewhat more powerful than the bristles of the original fourth 

 joint, the others are weak. All the joints are quite bare. 



Second antenna (fig. 23) : — The proportion between the protopodite 

 and the e x o p o d i t e is about the same as in the male, but they are somewhat smaller, the 

 protopodite being only about 0,4 mm. long. Endopodite: This is also somewhat smaller 

 than in the male. The bristles of the first joint are of the same type and relative length as in 

 the male. Second joint: This is somewhat less than half the length of the first joint. The distal 

 verruca that is characteristic for the male is absent. The longest of the f- and g-bristles is about 

 half as long as the shell or somewhat more (it measured 0,55 — 0,7 mm.), the other is about 

 a third or somewhat more of this length; both are narrow and have short, fine hairs, almost 

 bare. To the original third joint corresponds an exceedingly small verruca, situated- at the 

 place corresponding to that of this joint in the male; it is not bounded off from the original 

 joint. It has only one bristle, which is of about the same type and relative length as the longest 

 bristle on the end joint of this branch in the male. The endopodite is bare. 



Mandible: — This is quite similar in males and females or at any rate dimorphism 

 is scarcely perceptible. The only difference I could observe in the specimens investigated by 

 me was that the four bristles on the endite of the second protopodite joint were perhaps somewhat 

 longer in the males than in the females. 



Sixth 1 i m b (fig. 29) : — This is rather considerably smaller and weaker than that 

 of the male; the musculature especially is considerably more weakly developed. In order to 

 show the state of affairs with regard to size it may be pointed out that the male exopodite 

 of this limb is about twice as long as the female one (excluding, of course, the end bristles). 

 The endopodite is rather well marked off from the protopodite. (I cannot say anything 

 about the musculature because of the bad state of preservation of the material.) The bristles 

 are similar to those of the male. E x o p o d i t e: This has the same number of bristles as in 

 the male. First joint: The five ventral bristles are in most cases subequal and relatively about 

 as long as or somewhat longer than the corresponding bristles in the male; their length varies, 

 however, to some extent. Three of them are in most cases of the same type as those of the male, 

 two (in most cases nos. 3 and 5, counting proximally distally) have long hairs at the 

 middle. The bristle at the middle of the outside of this joint is of about the same type and 

 length as the two bristles just mentioned. The dorso-distal bristle, which has short, fine hairs. 



