8 BRITISH COPEPODA. 



well as in other Calanidce ; these last-named organs are 

 always most largely developed in the males, and it is 

 not unlikely that they are subsidiary sexual organs, pos- 

 sibly endowed with a highly-developed sensuous faculty. 

 Besides the forms of antennal appendages here noted 

 other modifications exist, of which the special uses are 

 at present unknown. 



The anterior antennas serve yet another essential 

 purpose, being adapted in the males as clasping organs ; 

 they, together with the fifth pair of feet, are in very 

 many species specially fashioned so as to insure a firm 

 grasp of the female. The number of joints found in the 

 anterior antennas varies from five or six in some semi- 

 parasitic species (Lichomolgus) and eight or nine in the 

 Harpacticidce, to twenty-four or twenty- five in the 

 Calanidce. In the females the antennas are always 

 alike on both sides of the body, but in the males 

 of many of the Calanidce the right antenna is modified 

 for the purpose of clasping ; while in all other non- 

 parasitic species the male antennas of both sides are 

 specialized for that purpose. In the semi-parasitic 

 Corycce-idce, Saphirinidce, &c., there is little or no 

 sexual difference in the anterior antennas, the clasping 

 function devolving on the posterior pair. The par- 

 ticular structural adaptations differ in different cases ; 

 in the Calanidce, as before stated, the right antenna 

 only is differentiated, the alteration consisting in one of 

 the joints not far from the apex being so articulated 

 as to form a hinge, by means of which the distal portion 

 of the limb can be flexed upon the basal portion. 

 Above and below the hinge the inner margins of the 



