a 
THE 
AMERICAN 
JOURNAL OF SCIENCE, &c. 
Arr. I.—Description of a Crustaceous Animal, belonging to the 
genus Caligus—C. Americanus ; by Cuarnes Picxerine, M. D. 
and James D. Dana, Members of the Yale Natural History So- 
ciety. 
Read before the Yale Nat. Hist. Soc., Feb. 20, 1838. 
Tue species of the genus Caligus, and of other allied genera, 
are commonly called fish-lice, in allusion to their parasitic mode 
of life. ‘The individuals which are the subject of the following 
remarks, infest the Common Cod* of this part of the American 
coast. 
During the fall of the year, when the shoal fish are brought to 
the New York market,} the Caligi are exceedingly abundant. Oc- 
casionally, forty or more individuals may be taken from a single 
fish. As the season advances, the fish are taken in fewer num- 
bers off Sandy Hook and Long Island, and afford a much smaller 
proportion of parasites. 'The Caligi are most numerous on the half- 
grown fish ; they are found indiscriminately on the head or different 
parts of the body, but never within the gill-covers. A European 
species has been said to live under the scales: we have never ob- 
served this peculiarity in the species on this coast; indeed, the 
closeness of the small scales of the cod, renders it impossible. 
* It has not been satisfactorily ascertained whether the cod of this coast is iden- 
tical with the European species, Morrhua vulgaris ; this, however, is the common 
opinion. 
t These investigations were made at the city of New York, and occupied the 
aoa ee of November Men together with the following months, December and 
.. AX XIV.—No. 2. 29 
