500 



PROCEEDINGS OF THE NATIONAL MUSEUM. vol. xxviii. 



This terminal portion represents the exopod and in many species of 

 both Caligus and Lepeophtheirus there is also a distinct endopod 



(e", fig\ 7), with two setse on its 

 apex attached to the base of the 

 exopod {Lepeophtheirus pectoral 7*, 

 Caligus rapax, etc.). 



The mouth opening is terminal 

 or termino-ventral and may be 

 either circular in outline ( Caligus 

 lionito, Lepeophtheirus edwardsi), 

 transversely elliptical ( Caligus ra- 

 pax), or even strongly lunate 

 ( Caligus curtus, Lepeophtheirus 

 pectoralis). 



Whatever its shape it is always 

 surrounded by a fringe of long 

 hairs. Often in the incision at the 

 center of the under lip is a small 

 tuft of hairs considerably longer 

 yet. In living specimens these 

 hairs are seen to be motile and 

 they must assist in drawing the 

 blood up the mouth tube by mak- 

 ing the joint at the mouth opening 

 tighter. 



The framework of the mouth is quite complicated and consists of 

 two sets or series of rods running lengthwise, connected by others 



Fig. 5. — The second antennae and the first 

 maxill.e of the adult caligus bonito. 

 Upper figure, the male; lower, the female.. 



a 



Fig. 6.— Mouth parts, a, dorsal surface of mouth tube of Lepeophtheirus hippoglqssi; b, 

 ventral surface; c, mandible; d, mandible of Caligus bonito; f, flexible flap at anterior 

 END OF cpper lip: r, ROD on lateral margin of framework of lower lip. 



which are transverse. There is first a long rod on either side, running 

 the entire length of the framework along the lateral margins and 

 furnishing the requisite support for the whole mass (r, fig. 6. and r', 



