HELMINTH FAUNA OF THE DRY TORTUGAS. 
By Epwin LINTON. 
INTRODUCTION. 
The material upon which the following report is based was collected 
at the Marine Biological Laboratory of the Carnegie Institution of Wash- 
ington, Tortugas, Florida, June 30 to July 18, 1906. A preliminary report 
was published in Year Book No. 5, of the Carnegie Institution of Wash- 
ington, pp. 112-117. 
This report, with a few emendations, follows: 
REPORT ON ANIMAL PARASITES COLLECTED AT TORTUGAS, FLORIDA, 
JUNE. s0.tO JULY 18)" 1906: 
In the table on pages 162, 163 will be found a list of the hosts which were 
examined for parasites, and a summary of the results of that examination, 
together with a few food notes. Where no food is recorded it is to be 
understood that either the alimentary canal was empty or the nature of its 
contents could not readily be identified. 
While a more comprehensive search, extending over not only a greater 
range of species than is included in the accompanying list of hosts but also 
over a larger number of individuals under each species, is desirable, and 
would doubtless add very many species of parasites, enough, I think, may 
be learned from the table to warrant the following general remarks on the 
helminth fauna of the Tortugas. 
I shall record also in this connection a few extracts from notes made at 
the time the material was collected. 
Acanthocephala.—Representatives of this order appear to be rare at 
the Tortugas. The species found in the frigate mackerel was Echinorhyn- 
chus pristis, which seems to be eminently a southern form, since it was found 
to be the most frequently recurring species at Beaufort, while a closely 
related species has a similar distribution in the fishes of Bermuda. 
Neither in the fishes of Beaufort, Bermuda, nor Tortugas have I found 
Echinorhynchi as abundant as in the fishes of northern waters. There thus 
appears to be the same contrast between tropical and northern forms shown 
in the distribution of the Echinorhynchi as in many other groups of organic 
forms. In this case, however, there does not appear to be a multiplication 
of species along with relative paucity of individuals, a condition which is 
characteristic of many tropical forms. 
Nematodes.—But few nematodes were found. Those found in the nurse- 
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