482 



PROCEEDINGS OF THE NATIONAL MUSEUM 



VOL. 88 



The female measures up to 12 mm. and the male up to 6 mm. It 

 has been found on the following hosts : Clupea vernaUs, Dorosoma 

 cepedianum, Pomolohus pseudoharengus^ P. strongyhwra marina^ and 

 Osmerus mordax from the Woods Hole region; Gasterosteus biacu- 

 leatus in the Gulf of St. Lawrence ; Microgadus tomcod^ Base Eiver, 

 Nova Scotia; Gtenolohrus adspeims^ Casco Bay, Maine, Great Egg 

 Harbor, N. J., Key West, Fla., Patapsco River, Baltimore City, a 

 fresh- water tow^ in the Shubenacadie River, Nova Scotia; and from 

 the "toadfish," Shell Point, Fla. 



ARGULUS SIAMENSIS Wilson 



FlGTTRE 24 



Argulus siamensis Wilson, 1926, p. 361, pi. 22. 



Carapace ovate, reaching fourth appendages in the female, over- 

 lapping abdomen in the male; cephalic area narrow, posterior sinus 

 broad. Abdomen elliptical, anal sinus deep, tips acute, slightly 

 divergent. Respiratory areas with anterior one club-shaped and 

 curved around posterior one, but slenderer than that of stizostethii 

 (fig. 24, a). 



PiGUKB 24. — Argulus siamensis: a. Respiratory areas ; ft, male accessory organs of third 

 and fourth legs ; c, ribs of suction cups. 



Antennae with slight anterior knob, lateral hook long; ventral 

 spine blunt, spine at base of first antennae long and blunt, that at 

 base of second antennae small and transparent, postantennal spine 

 long and blunt. First antennae relatively stout, second antennae 

 very long. Second maxillae with broad basal plate, teeth broad and 

 blunt, both pairs of spines near midline of body small and blunt. 

 Suction cups with ribs of four or five imbricate plates and a longer 

 basal one (fig. 24, c). 



