neto Parasitic Copepods on Fish. 369 



Female. — Head of large size, lonj^er than broad, lar^^est at 

 the base, which is slightly rounded ; it is strongly arched 

 dorsally from side to side, the margin folding inwards on the 

 under surface ; in front the border is convex and prominent, 

 showing no median notch, from the underside of wliich 

 frontal border the six-jointed setiferous anterior antennse are 

 seen. 



Thorax seen from the dorsal surface divided into three 

 segments, each having a median indentation posteriorly; 

 they are broader than the head and are together somewhat 

 longer : the anterior segment is but indifferently marked off; 

 this is the true second thoracic segment bearing the second 

 pair of thoracic limbs, the first being united with the cephalic 

 portion ; it is less wide than the following segments and very 

 short : the second free segment is much broader than long, 

 with rounded sides, from under which can be seen projecting 

 the tliird pair of limbs ; the third free thoracic ring is slightly 

 smaller than the last, but of similar shape, being not so long 

 as broad and deepl}^ cut away posteriorly ; the sides of 

 these segments are deeply pigmented, and the alimentary 

 canal is easily visible down the centre ; the usual posterior 

 tunic or plate common to the whole genus appears to be, 

 however, entirely absent, the abdomen being quite bare, 

 projecting between the two greatly elongated processes repre- 

 senting the fourth pair of limbs; on either side of it from the 

 posterior edge of the lobe of the last segment, is seen a small 

 rounded flap or plate partially covering the base of the fourth 

 pair of limbs ; these may be the rudiments of the dorsal tunic. 

 The ahdomen is rather longer than the last thoracic seg- 

 ment ; it is composed of three distinct portions, the second 

 partially overlapping the third : the first is of a rounded 

 shape, but broader than long ; the second is pointed at the 

 extremity, it is constricted in the middle, dividing it into two 

 parts ; to the upper and wider are attached the ovarian tubes, 

 to the narrower the two stalked dark spermatophores. The 

 third abdominal joint is oblong in shape, traversed by the 

 intestinal tube ; the anal opening is seen at the end between 

 the two caudal plates, which are oval in shape, somewhat 

 divergent, and placed on the under border. 



Fi-om the ventral side one sees the six-jointed setiferous 

 anterior antennae, and placed far forward the triarticulate 

 posterior antennce ; the first two joints of the latter are very 

 broad and muscular, the last in the form of a curved hook : 

 beneath these on the median line is found the mouth, of a 

 pointed conical shape ; on each side of this near the base a 

 slender triarticulate and a thicker biarticulate process can be 



