THE APPENDAGES, THEIR INTERRELATION AND FUNCTION 



303 



as already mentioned, show sexual dimorphism and specific variation in their armature, and may have 

 some special secondary sexual function. The fact that in some species, even in the male, their free 

 tips have a structure similar to the sensory tube-setae may mean that they also are sensory. 



1° ks sh 



Fig. 1. Conchoecia borealis antipoda. Right antennule from inside. A, female; B, male with frontal organ, f.o. frontal organ; 

 h.s. hooked seta; sh, shaft; a and c, tube setae; b and d, secondary setae (tube setae in female); e, principal seta. 



Fig. 2. C. borealis antipoda. Female with left valve of carapace removed, antennal exopod omitted. a lt antennule; a t s, prin- 

 cipal seta of antennule; a 2 , antennal shaft; a 2 en, antennal endopod; c.f. caudal furca;/.o. frontal organ; ist, isthmus linking 

 body to carapace; lb, labrum; tnn.b. mandibular basis; mn.c. mandibular coxa; tnn.p. mandibular palp; mx lt maxillule; 

 mx 2 , maxilla; tr v first trunk limb; tr„, second trunk limb. 





Antennae (Fig. 2, a 2 , Fig. 3) 



The antennae are biramous with the exopod composed of eight or nine articles and the endopod small 

 with not more than three articles. The endopod shows sexual dimorphism. As in most Myodocopa, 

 each relatively enormous, broadly expanded shaft contains a powerful musculature. Each articulates 



