132 
specimens: USNM Helm. Coll. No. 33131. 
PREVIOUSLY REPORTED HOSTS AND LOCALI- 
TIES: Reported from the same species of host 
off Havana, Cuba, by Vigueras (1935). 
Capsala biparasitica (Goto, 1894) 
Price, 1938 
synonyms: Tristoma biparasitica Goto, 1894. 
host: Yellowfin tuna, Neothunnus macrop- 
terus (Temminck and Schlegel). 
location: Firmly attached to carapace of 
copepods found in gills. 
locality: 02° 14' N., 159° 59' W. (vicinity 
of Christmas Island). 
specimens: USNM Helm. Coll. No. 38134. 
PREVIOUSLY REPORTED HOSTS AND LOCALI- 
TIES: Goto collected this species of trematode 
from a copepod (. Parapetalus sp.) on Thynnus 
albacora from Misaki, Japan. 
discussion: The copepod involved in the 
present record is Elytrophora sp. A comparison 
of these host records is of particular interest 
because the trematode is a hyperparasite and 
because in each collection both the copepod 
hosts are caligid copepods and the fish hosts 
are closely related. 
Family HEXASTOMATIDAE 
Hexostoma grossum (Goto, 1894) 
Sproston, 1946 
synonyms: Hexacotyle gr ossa Goto, 1894. 
HOST: Bigeye tuna, Parathunnus sibi (Tem- 
minck and Schlegel). 
location: On gills. 
LOCALITY: 02° 45' N., 158° 05' W. 
SPECIMENS: USNM Helm. Coll No. 38133. 
PREVIOUSLY REPORTED HOSTS AND LOCALI- 
TIES: On gills of Thynnus sp. from Misaki, 
Japan (Goto, 1894); type host corrected to 
Parathunnus sibi and reported on gills of Ka- 
tsuwonus vagans and Thunnus orientalis , and on 
Seriola quinqueradiata from Japan (Ishii and 
Sawada, 1938). 
PACIFIC SCIENCE, Vol. XII, April, 1958 
Order DIGENEA 
Family HEMIURIDAE 
Hirudinella marina Garcin, 1730 
synonyms: Nigrelli and Stunkard (1947) 
include a very lengthy list of possible syno- 
nyms of this species. 
HOST: Yellowfin tuna, Neothunnus macrcp- 
terns (Temminck and Schlegel). 
LOCATION: In stomach. 
LOCALITY: 06° 20' N., 162° 30' W, (vicinity 
of Kingman Reef) . 
PREVIOUSLY REPORTED HOSTS AND LOCALI- 
TIES: Nigrelli and Stunkard (1947) include a 
long list of hosts, mostly of scombriform 
fishes, including N. macroptems from C. San 
Lucas, Lower California, Pacific. 
DISCUSSION: In the course of the examina- 
tion of stomach contents of yellowfin and 
bigeye tuna from the central Pacific, King and 
Ikehara (1956) encountered large muscular 
trematodes. They report an infection rate of 
32 per cent for 166 bigeye and 26 per cent for 
the 439 yellowfin they examined. Since Ni- 
grelli and Stunkard recognize only two spe- 
cies of Hirudinella , one in the wahoo, H. 
ventricosa , and one in other hosts, id. marina , 
it is very likely that these worms belong to 
the latter species. 
Hirudinella ventricosa Pallas, 1774 - 
SYNONYMS: Nigrelli and Stunkard (1947) 
list nine possible synonyms. 
HOST: Wahoo, Acanthocybium solandri (Cu- 
vier and Valenciennes). 
location: Stomach. 
locality: Christmas, Fanning, Washing- 
ton, Palmyra islands, and Kingman Reef. 
PREVIOUSLY REPORTED HOSTS AND LOCALI- 
TIES: Acanthocybium solandri in the Atlantic 
and Pacific; from the Pacific it has been re- 
ported from Panama, Mexico, Equador, and 
the Marianas Islands (Nigrelli and Stunkard, 
1947). 
discussion: Nigrelli and Stunkard (1947) 
have made a thorough study 'of this genus and 
