[57] MATERIALS FOR A HISTORY OF THE SWORD-FISHES. 345 
T. cocecineum is almost orbicular in outline and quite flat. The pos- 
terior border is never scalloped, as in a closely allied species. The 
diameter of the posterior sucker is nearly equal to one-fifth the length 
of the body, and presents seven rays. The total length of the animal 
is about 25 millimeters. Its color, according to some authors, is rose-red, 
but, according to others, red approaching vermilion. Like all other 
species of the genus, it lives in the gills of the fish it infests. 
5, TRISTOMA PAPILLOSUM, Diesing. 
Tristoma papillosum, DIESING, Nov. Act. Nat. Curios. xviii, 1836, pp. 313-316, 
pl. xvii, figs. 13-18. 
Tristomum papillosum, DIESING, Systema Helminthum, i, 1850, pp. 430-431. 
This fluke is oblong in outline. The posterior sucker is quite as 
large as that of the preceding species, but is situated nearer the pos- 
terior margin. The dorsal surface is covered with many little papillary 
appendages. The animal is about nine-tenths of an inch in length and 
three-tenths in breadth. Its color is a dusky yellowish white. It lives, 
in company with the preceding species, in the gills of the Sword-fish and 
other fishes. 
CESTODA. 
6. TETRARHYNCHUS ATTENUATUS, Rudolphi. 
Tetrarhynchus attenuatus, RUDOLPHI, Entozoorum Synopsis, i, 1819, pp. 130, 
449, 688. 
Tetrarhynchus discophorus, BREMSER, Icones Helminthum, 1824, pl. xi, figs, 
14-15. 
The tape-worms of this genus possess a very short body, a long and 
narrow neck, and a head furnished with four long proboscises, armed 
with a great number of recurved hooks. The species under considera- 
tion varies in length from 2 to 5.9 millimeters. The head is somewhat 
conical in shape, and bears two round and strongly concave suckers. 
The neck is narrow behind, and transversely rugose. As it is the only 
species of the genus found in the Sword-fish, it cannot be easily mistaken. 
It has been found on the gills of the Sworn eae and also in the walls 
of the abdomen. 
7. BOTHRIOCEPHALUS XIPHLA (Gmelin) True. 
Echinorhynchus xiphiw, GMELIN, Linn. Syst. Nat. vi, 1788, p. 3047. 
Bothriocephalus plicatus, RUDOLPHI, Entozoorum Synopsis, 1819, pp. 136, 479, 
pl. iii, fig. 2. 
This tape-worm varies in length from 30 to 300 millimeters. Its 
head is elongated-arrow-shape or fusiform in outline. The anterior artic- 
ulations of the body are very narrow, but they widen towards the cen- 
ter; the posterior ones, again, are narrow. It usually inhabits the rec- 
tum of the Sword-fish, but has been also occasionally found buried in 
the walls of the intestines. 
b. The Crustacean parasites—The Crustacean parasites of the Sword- 
fish belong to the group known as Copepoda. They are five in number. 
