studies on marine Oslracods 749 



haired bristles ventrally. Most of these are usually of the tube-bristle type and are about as 

 long as the proximal height of this joint; three (two) of these are situated about half-way along 

 the joint, the two others are placed distally. Laterally at about the middle of this joint there 

 are two bristles, of about the same length as the former ones, but W'ith long, soft hairs, and short 

 hairs distally; they are pointed. The bristle situated dorso-distally on this joint is very long, 

 being about as long as the total length of the first and second exopodite joints; it has short, 

 fine hairs and is pointed. The three bristles on the second joint have short, fine hairs. The two 

 ventral ones are subequal, somewhat more than half the length of this joint. The dorsal one is 

 about as long as this joint. The dorsal one is usually pointed, the ventral ones usually of the 

 tube-bristle type. End joint: The middle one of the three bristles is rather powerful and about 

 as long as the total length of the two distal exopodite joints; it is finely pectinated; its point 

 is in most cases of about the tj'pe reproduced in fig. 28 of Conclioecia symmetrica. The two others 

 are somewhat shorter and weaker and have short, fine hairs; they are of the tube-bristle type 

 or are pointed. Pilosity: Proximo-anteriorly on the protopodite there are groups of short, fine 

 hairs; the first exopodite joint has groups of soft hairs, principally proximo-ventrally and dor- 

 sally, but sometimes medio-distally as well. 



Sixth limb (fig. 28): — This is large and powerful and has a ver}^ powerfully developed 

 musculature; it is used as an auxiliary organ in swimming: The protopodite is unjointed. 

 Endopodite: This is quite joined to the protopodite; its special musculature has quite 

 disappeared. It has two short-haired, pointed bristles, one of which is about as long as the 

 width of the protopodite (calculating from front to back), the other is often only about half 

 as long; both are attached antero-ventrally on this part. Exopodite: First joint: Scattered 

 along the ventral side, somewhat medially, there are five bristles of the same t'V'pe as the two 

 just mentioned, about as long as or rather slightly shorter or longer than the proximal height 

 of this joint. Laterally at about the middle of this joint there is a single bristle of the same 

 type and about the same length as the ventral bristles. The dorso-distal bristle on this joint 

 is bare or almost bare, pointed, and about as long as or somewhat shorter than half the length 

 of the second exopodite joint. Second joint: Ventrally at or somewhat in front of the middle 

 there are (contrary to all the other sjjecies of this sub-family known to me) two subequal, bare or 

 almost bare, pointed bristles, one situated somewhat distally of the other, in most cases not 

 quite half the length of this joint. Third joint: The two bristles are bare or almost bare, pointed 

 and sube(jual, almost as long as this joint; they are situated somewhat in front of the middle 

 of the joint. The three bristles of the fourth joint are subequal and all of the same type; they 

 are about as long as or even somewhat longer than the exopodite; along the distal two-thirds 

 of their length they are furnished with rather long natatory hairs, and are evenly and rather 

 strongly curved ventrally (when in a state of rest these three bristles point dorso-posteriorly; 

 their points are often visible at the postero-dorsal corner of the shell; it ought perluips to be 

 pointed out that these three bristles do not change into sensory organs distally). Pilosity: 

 Anteriorly on the protopodite and the endopodite there are a rather sparse number of rather 

 short, soft hairs. On the first exopodite joint there is a group of simihir hairs jiroximo-laterally, 

 somewhat ventraUy. 



