CRUSTACEA. 
165 
Portunus marmoreus, Leach ; Bell, op. cit. p. 105. 
On the West Sands after storms. Bather rare. 
Portunus Jiolsatus , Fab.; Bell, op. cit. p. 109. 
Not uncommon in the stomachs of cod and haddock. Saccu- 
lina occurs on this species occasionally (Plate IX. figs. 14 & 15). 
Portunus pusillus , Leach ; Bell, op. cit. p. 112. 
Occasionally from deep water, and rather common in the 
stomachs of the haddock and flounder. 
Genus Portumnus, Leach. 
Portumnus variegatus , Leach ; Bell, op. cit. p. 85. 
Abundant on the sandy ground off the West Sands. 
Genus Carcinus, Leach. 
Carcinus mamas 7 L.; Bell, op. cit. p. 76. 
[Plate V. figs. 7 & 8, and Plate IX. figs. 10-13.] 
Everywhere abundant between tide-marks and in the 
laminarian region. Occasionally used as bait. Swarms in 
the zoea-stage occur in autumn at the surface of the water in 
the bay; they are almost invisible with the exception of the 
greenish-blue eyes. 
This crustacean has nine branchiae:—the first rudimentary, 
and attached to the horizontal portion of the first pair of 
foot-jaws (Plate V. fig. 7) ; the succeeding, rather long and 
delicate organs, fixed to the second pair of foot-jaws on 
opposite sides of the horizontal portion ; while six are at¬ 
tached to the body of the animal (four being prominent) 
as in allied forms. The flabellum of the first pair passes 
between the four prominent and larger branchise and the 
apodematous region, so as to sweep their inner surface; 
while the organ of the second pair goes between the 
same portion of the shell and the fifth and sixth branchiae 
(counting from behind), and may also affect the exposed 
surface of the seventh, which lies in the groove anteriorly. 
The long and finely curved flabellum of the third pair of 
foot-jaws curves externally, so as to brush all the seven. 
