WILSON, PARASITIC COPEPODS FROM JAPAN. 15 



fourth pairs are uniramose, the rami of the third pair indis- 

 tinctly jointed, those of the fourth pair definitely one-jointed. 

 All the rami are well armed with setae. 



Color (preserved material) a yellowish-white; egg strings 

 orange-yellow. 



Total length 6.25 mm. Cephalothorax 3 mm. long, O.8O 

 mm. wide. Trunk 3. 40 mm. long, greatest diameter 2. 15 mm. 

 Egg coils 3 mm. long. 



Specific characters of youngest development stage. 

 Head, thorax, and trunk in the same straight line, the poste- 

 rior end of the trunk barely protruding from the outer sur- 

 face of the fish's eye. Cephalothorax much larger than the 

 trunk, about three times as long as wide; f rontal processes 

 well formed but much smaller than in the adult and not 

 lobed. Only the flattened bases of the soft horns present, 

 their outer margins showing irregular knobs where the future 

 rami are to develop. The chitin horns on the fourth seg- 

 ment are very short, with the rami indicated by a knob at 

 each distal corner. 



The neck behind these horns is only two-fifths the width 

 of the rest of the thorax and is separated from the trunk 

 by a distinct groove. 



The trunk is an ellipsoid, the length about twice the 

 greatest diameter, with a pair of tiny anal laminae at the 

 posterior end, each armed with a singie seta. 



Total length 2. 7 o mm. Cephalothorax 1.8 5 mm. long, 

 0.6 6 mm. wide. Trunk O.75 mm. long, 0.4 o mm. wide. 



Specific characters of cider development stage. Ceph- 

 alothorax bent back at an angle of 45 degrees with the 

 trunk axis, but not twisted sidewise; f rontal processes larger 

 and lobed. Soft horns and chitin horns of the fourth seg- 

 ment with short but definite rami. Trunk flattened slightly 

 sidewise, the dorsal margin becoming more straight, the ven- 

 tral one more convex. Anal laminae still visible at the 

 posterior end near the dorsal surface, but destitute of setae. 



Total length 4 mm. Cephalothorax 2. 4 o mm. long, 0.6 6 

 mm. wide. Trunk Leo mm. long, 0.66 mm. in greatest dia- 

 meter. 



Remarks. These specimens fully confirm the species 

 and establish it upon a secure basis. This parasite evidently 



