60 Alf Wollebæk. [No. 12 
These two sub-branches (a.i. and a.m.) appear when only slightly | 
magnified to be practically identical in size and structure. When 
much enlarged however, (fig. 4 b) considerable differences are 
revealed. The sub-branch situated nearest the swimmeret (a.m. ap- 
sl d 
N KE 
SYN 
AN Eg 
C2 Cr 
| ( E 
415 
Fig. 4. Pandalus borealis Kr. 
a. 2nd Pleopod of a male; a.i. appendix interna; a.m. appendix masculina; r.i. inner blade 
(endopodite); r.e. outer blade (exopodite); c. cincinnuli; d. inner blade of Ist pleopod of 
a male; e. same of female. 
pendiz masculina) which is the organ of copulation, is straight 
and furnished at the tip with åa number (about eight) of com- 
paratively stout setae almost as long as the appendix itself. These 
setae are attached in a spiral arrangement round the distal end of 
