WILSON, PARASITIC COPEPODS FROM JAPAN. 11 



It does not always follow the exact pattern shown in 

 the figures, but approximated it in 35 out of the 40 females 

 examined. The other five were also distorted, but not 

 symmetrically so. 



Choudracaiithus sixteni New Species. 

 Pl. 3, figs. 27—30; 4, figs, 31—32. 



Höst and record of specimens. Six females vvith egg 

 strings and with attached males were obtained from the in- 

 side of the pharynx of a species of halibut at Misaki, Japan, 

 April 25, 1914. 



Specific characters of female. General body form short 

 and ston t; head distinctly separated from the first thorax 

 segment, longer than wide and somewhat narrowed anteriorly, 

 with the bases of the maxillipeds projecting laterally. All 

 four thorax segments well defined; the first one is the shor- 

 test and narrowest and its lateral margins are bluntly poin- 

 ted; the third one is the longest and widest, with strongly 

 convex sides. The fourth joint is prolonged at its posterior 

 corners into short, stout, and bluntly rounded processes. 

 The genital segment is minute, only about a sixth as wide 

 as the fourth segment, and is sometimes almost hidden by 

 the posterior processes and egg strings. The latter are 

 straight and cylindrical, as long as the entire body and 

 somewhat tapered posteriorly. 



The abdomen is one-celled, minute and without anal 

 laminae. 



The first antennae are rather long and slender and very 

 indistinctly jointed; the second pair are of the usual form, 

 with stout basal joints and powerful terminal claws. The 

 mandibles are rather large and acuminate and are armed 

 with small but sharp teeth. The cutting blade of the maxillae 

 has a row of teeth along its posterior börder, which diminish 

 in size from the tip inwards and wholly disappear at about 

 the center. In the maxillipeds the terminal joint is prolonged 

 inside the base of the claw into a large knob covered with 

 small spines. 



Color (preserved material) a uniform yellowish-white. 



Total length 6 mm. Greatest width 2 mm. Egg strings 

 5.75 mm. long. 



