COPEPODS OF THE WOODS HOLE REGIOlSr 



17 



Fe^nale.— Carapace elliptical, longer than wide, the lateral lobes 

 not reaching the urosome; posterior sinus broadly triangular and 

 very shallow. Urosome elliptical, longer than wide, cut less than a 

 fourth of its length, caudal rami basal. Teeth on basal plate of 

 maxilliped long and blunt; the two portions of each respiratory area 

 widely separated, the posterior one with a toothed outer margin; 

 each supporting rod of the maxillary disks made up of a basal 

 segment, enlarged at its distal end, and eight or nine sliort segments 

 more or less tele- 

 scoped. Swimming 

 legs without flag- 

 ella. Total length, 

 5-7 mm. Width of 

 carapace, 3-4 mm. 



Male. — Size, 

 shape, and general 

 proportions similar 

 to those of the 

 female. Proximal 

 basipod segment of 

 third legs with a 

 large thumb- 

 shaped process ex- 

 tending forward from the anterior distal corner ; peg on fourth basi- 

 pod in the form of a flattened spherical ball, attached to the leg by a 

 short neck. Total length, 5-7 mm. Width of carapace, 3-4 mm. 



Remarks. — This species has a larger number of hosts than any 

 of the other argulids of the region, and it is worthy of note that all 

 of them are fishes that frequent the bottom of the ocean. 



ARGULUS ALOSAE Gould 

 FiGtJRE 6 



Argulus alosae Gould, Report on the Invertebrata of Massachusetts, p. 340, fig. 

 1, 1S41.— Rathbun, Proc. U. S. Nat. Mus., vol. 7, p. 485, 1884.— Wilson, 

 Proc. U. S. Nat. Mus., vol. 25, p. 707, pi. 12, 1902. 



Host and localitT/.— Outside surface and rarely the gill chamber 

 of the common alewife, Pomolohus pseudoharengus^ and the Ameri- 

 can smelt, Osmertis mordax^ both in the Woods Hole region. 



Distribution.— Vatohogne, Long Island, N. Y., and Key West, Fla. 

 (Wilson) ; Gulf of St. Lawrence on Gasterosteus hiaculeatus (Whit- 

 eaves) ; Bass River, Nova Scotia, on Microgadus tomcod (Wilson). 



Color.— Fale yellowish white, mottled along the lateral margins of 

 the carapace and across its lateral lobes with a stippled design in 

 cinnamon-brown. Eyes, testes, semen receptacles, and eggs dark 

 reddish brown. 



Figure 5. — Argulus mcgalops: a. Female, dorsal (variant) ; 

 ft, supporting ribs of sucking disk 



