HELMINTH FAUNA OF THE DRY TORTUGAS. 



BY EDWIN 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, Tortngas, 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 30 TO JULY 1 8, 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- 

 c Ints 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- 



