646 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. xxvii. 



horseshoe suture is longer and narrower than in mnericanus^ and from 

 near its base two sutures radiate outward into the lateral area. The 

 thoracic area is separated into an anterior crescent-shaped and a pos- 



FiG. 23. — Ventral view of female argulus versicolor. 



terior rectangular portion, the tormer of which is much wider than 

 the latter and follows closely the posterior curve o^ the horseshoe. 



Fig. 24. — Detail of antenx.e of argulus versicolor. 



Ventral m/i'face (tig. 23). — The frontal lobe is simple and, together 

 with the anterior half of the lateral areas, is covered with inconspicu- 

 ous triangular spines. The antenna are of good size and well armed; 



