414 PROCEEDINGS OF Till: X \TI(>\ l/, MUSEUM. vol.38. 



Genus ACARTIA Dana, 1846. 



ACARTIA TONSA Dana. 



Acartia tonsa Dana, Proc. Amer. Acad. Arts and Sci., 1849, vol. 2, p. 26. — Gies- 

 brecht, Fauna und Flora des Golfes von Neapel, vol. 19, 1892, p. 508, 5 

 figures. Giesbrecht and Schmeil, Das Tierreich, Dec. 1898, p. 154.— 

 Wheeler, Bull. U. S. Fish Comm., vol. 19, 1900, p. 183, figs. a-d. 



Length. — Female, 1.3 to 1.5 mm.; male, 1.05 mm. 

 Characters. — Rostral filaments present. Last thoracic segment 

 rounded on sides. Abdomen without spines. Anal segment hairy on 

 sides, hut in male with fine points on the second segment. Middle 



segment of female fifth foot about as long 

 as broad. Terminal claw more than twice 

 as long as the terminal segment, straight, 

 and alike for each foot. 



Wheeler, 1900, page 183, shows a figure 

 of the fifth foot of the female which evi- 

 dently is very exceptional; probably that 

 of a mutilated specimen, or of a regene- 

 rated leg. All studied by the writer were 

 as in fig. 5. 



Occurrence. — One of the commonest cope- 



Fig. 5. — Acartia tonsa. Fifth i i ? , i i r e ,i -&• \ r\ 



POOT OF FEMALE X 500. ])«»( U t a k.M . I |(. .. 1 t l.C wl Ul H of t llC Fish CoDl- 



mission at Woods Hole, summer (Wheeler). 

 Also Plymouth Harbor, and Gulf Stream 70 miles south of Marthas 

 Vineyard (Wheeler). Also occurring abundantly in nearly all the 

 tows examined by the writer from the Woods Hole region, even in the 

 Eel Pond and the brackish water ponds of the vicinity. In fact, 

 nearly all the pelagic copepods of these ponds were this species. 



Distribution. — Port Jackson, New South Wales (Dana); west coast 

 of South America, between Valparaiso and Callao (Giesbrecht). 



Genus TORTANUS Giesbrecht. 



TORTANUS DISCAUDATUS (Thompson and Scott). 



Corynura discntiihiln Thompson and Scott, Proc. Liverpool Biol. Soc., vol. 12, 



1897, p. SO, pi. (I, figs. 1 -11; pi. 7, figs. 1, 2. 

 Corynura bumpimi Wheeler, Hull. I'.S. Fish Comm., vol.19, 1900, p. 185, figs. a-f. 

 Tortanus discaudatus Giesbrecht and Schmeil, Das Tierreich, Dec., L898, |>. 158. — 



Van Breemen, \'<>r<lisches Plankton, VIII, Copepoden, p. L62, figs. u-c. 



Length. — Female, 2.25 nun.; male l.S to 2 nun. Very similar to 

 /'. gracilis (Brady) but with the right furcal branch and its spine-like 

 outer bristle innch more thickened. 



Endopodite of firsl leg three-segmented, which is very unusual for 

 Tortanus. 



