studies on marine Oslrarods 611 



short hairs, is of the tube-bristle type or is well pointed distally (the latter character varies even 

 within the species). At or most frequently somewhat distally of the middle of this joint, laterally, 

 there is a single bristle, in most cases about as long as or somewhat shorter than the former one, 

 sometimes with short hairs, sometimes with rather long hairs at the middle, in most 

 cases well pointed distally. One or two of the other bristles of this joint are situated ventero- 

 medially at or somewhat proximally of half the length of the joint; a group (three to five) are 

 situated ventrally often somewhat proximally of half the length of the joint; a group (two to 

 four) are situated ventrally near the distal boundary of the joint. These bristles vary to a rather 

 great extent both in number, length and type, not only from one species to another but also 

 often within the same species; a larger or smaller number of them are always of the tube-bristle 

 type; sometimes they all have short hairs, sometimes one or more of them have rather long 

 hairs at the middle. Second joint: The three bristles on this joint are either subequal or else 

 the dorsal one is slightly shorter or longer than the two ventral ones; they are in most cases 

 about as long as or somewhat shorter than this joint, always with short hairs and are most frequently 

 of the tube-bristle type. Of the three bristles on the end joint the middle one is rather powerful, 

 in most cases about as long as or somewhat longer than the second exopodite joint, finely pectin- 

 ated. (Its point — like the points of the two claws on the endopodite — is of about the same 

 type as is reproduced in my fig. 28 of C. symmetrica.) The two other bristles on the end joint 

 have short hairs and are tube-bristles; the dorsal one is in most cases about as long as or rather 

 slightly shorter than the middle claw, the ventral one is most frequently about as long as or 

 somewhat longer or shorter than half the length of the middle claw. The normal type of this 

 limb described above agrees fairly closely with my fig. 27 of C. symmetrica. The pilosity varies 

 on this limb, sometimes even within the species. 



Sixth limb: — For the same reasons as in the case of the mandible, maxilla and 

 fifth limb it seemed to me most convenient to give here in the genus description an account of 

 the , .normal type" of this limb found by me; consequently in the following descriptions of 

 species only such characters are included as differ more or less essentially from this type. 



Contrary to the immediately preceding limbs this one shows rather great dimorphism. 



Male: — This is large and powerful with very powerfully developed musculature 

 and is used as an auxiliary organ in swimming. The p r o t o p o d i t e is in most cases unjointed, 

 sometimes it shows a more or less distinct division into two joints. The endopodite is 

 only partly joined to the protopodite ; remains of its musculature can be observed. In most cases 

 it has two (in exceptional cases one) bristles, which are most frequently subequal and about 

 as long as the proximal height of the first exopodite joint, in most cases well pointed and 

 with rather long hairs at the middle, short hairs distally. Exopodite: First joint: 

 This joint usually has dorso -distally a short tube-bristle with short hairs. In exceptional 

 cases this bristle is not found. Laterally, somewhat disto-dorsally of the middle of this joint, 

 there is usually a single bristle, in most cases somewhat shorter than the distal height of this 

 joint and in most cases furnished at the middle with rather long hairs and with short 

 hairs distally; it has a fine point. This bristle may in rare cases also be missing. More or less 

 scattered along the distal part of the ventral side, partly somewhat medially and partly somewhat 



