REVIEW OF GENUS ARGULUS — MEEHEAN 479 



suction cups supported by 2 long segments in ribs ; 

 dorsal ridges of carapace branched at the anterior 



end; fresh water appendiculosus (p. 512) 



d^. Teeth of second maxillae very sharp ; no spine at base of 

 first antennae ; ribs of suction cups composed of rods. 



e\ Ribs of suction cups with 8 or 9 rods : lateral hook of 

 first antennae short but curved back on itself; fresh 

 water lepidostei (p. 514) 



e^ Ribs of suction cups with about 12 to 18 rods; tip of 

 first antennae biramous, with one of the branches 

 biramous ; abdomen heart-shaped in female, with lat- 

 eral projections on the anterior edges in male ; 

 fingerlike protuberances on distal anterior end of first 

 segment of endopod on third and fourth thoracic ap- 

 pendages; freshwater nobilis (p. 515) 



ARGULUS STIZOSTETHII KelJicott 



FlGIRE 22 



Argulus stizostcthii Kellicott, 1880, p. 53. — Wilson, 1902, p. 713, pi. 17. 

 Argulus canadensis Wilson, 1916, p. 348, pi. 60; 1936a, p. 355, figs. 1-9. 



Carapace elliptical, reaching to second or third swimming append- 

 ages, sinus shallow; cephalic area prominent, projecting slightly 

 anteriorly. Abdomen somewhat elongate with sides parallel, anal 

 sinus deep, tips of abdomen pointed and diverging somewhat, anal 

 furcae basal. The respiratory areas are peculiar in that the anterior 

 one is prolonged laterally around the posterior one in such a way as 

 to be club-shaped instead of rounded (fig. 22, a). As the type of 

 canadensis has a very broad mesial respiratory area, the inner edge 

 may easily have been overlooked by Wilson in his description. 



The hook on the anterior surface of the first antennae is tight 

 against the body of the antenna in the type of canadensis instead of 

 having the usual elongate base ; spine present on midventral surface 

 of antennae and at the base. Spines located at the base of the second 

 antennae, near the midline of the body, and the postantennal spines 

 are stouter than the others. The ribs of the suction cups are com- 

 posed of a stout pedestal with 10 or more apparently imbricate 

 plates (fig. 22, h). Second maxillae stout; basal plate large and 

 broad with a large pad; teeth small and sharp, widely separated; 

 two usual pairs of spines are located near the midline of the body 

 but the anterior pair are stouter. 



Flagella are lacking on the swimming appendages; female with 

 a small rounded natatory lobe on the posterior surface of the coxa 

 on the fourth appendages; basal segments stout. Second appendages 

 of male (fig. 22, c) with the usual bilobed flap on the coxa. Basis of 

 third appendages much abbreviated, with a papilla across the ante- 



