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PARASITIC HABITS OF CRUSTACEA. 943 
Isopod form, but the female by excessive growth becomes 
five or six times as large, deformed in shape, and firmly 
adherent in the gill-cavity of its host, where it produces a 
deformity and enlargement of the carapax, looking like a 
large tumor. Jone thoracicus infests a species of Calianassa ; 
Bopyrus squillarum victimizes a species of Squilla; and B. 
Hippolites infests various northern species of Hippolyte. It 
was observed last season by Mr. S. J. Smith and the author, 
at Eastport, Me., on H. Sowerbyi. Several other species 
are known having similar habits. 
Among the Amphipods we find Themisto and Hyperia, 
parasitic on the large jelly-fishes of our coast, especially 
Cyanea and Aurelia. Hyperia is very common, and may 
be known by its large head and eyes and swollen body, 
which is usually of a dull reddish color. .They live and 
breed in cavities that they themselves form in the disk of 
the jelly-fishes, by eating away its soft substance. They 
also live among the mouth-folds and ovarial lobes, often in 
large numbers and of ali sizes; but they occasionally leave 
their victim for a time and swim freely in the water. Mr. 
Smith has reared our native species by feeding them on 
fragments of jelly-fishes, and ascertained that they undergo 
considerable changes, the antennz becoming shorter at suc- 
cessive moults, showing that some of the nominal species, 
on the length of these organs, are merely stages of 
growth of one species. Several other parasitic Amphipods 
Were observed by Mr. Smith and the writer, at Eastport. 
One small species with bright golden eyes lived in the in- 
terior of Modiolaria levigata. Another pretty, pale-pink, 
smooth, red-eyed species was found repeatedly living par- 
asitically in the stomach of our large Red Sea-anemone 
(U; rticina crassicornis), but was seldom seen until the Urti- 
|. Gina had been placed in alcohol, when several would often 
come forth and move about for a short time, but occa- 
Stonally they were observed to come forth voluntarily, and 
after Swimming about for some time would suddenly dart 
