[457] INVERTEBRATE ANIMALS OF VINEYARD SOUND, ETC. 163 
tain species have been found in crustacea, others in mollusks, &e. Mr. 
A. Agassiz has briefly described, but not named, a remarkable worm 
that he found very common in the jelly-fish, Mnemiopsis Leidyi, and the 
young of this or a different species was observed by me inthe same Aca- 
leph. It appeared to be a species of Scolex. It was pale purple, with 
light yellowish orange stripes. I have previously mentioned a round 
worm (Ascaris?) which frequently occurs in winter in one of our species 
of Sagitta. 
Most of the species that, in the adult state, inhabit fishes, live while 
young, or in the larval stages, in smaller fishes, or in other animals, 
upon which the larger fishes feed, and from which they thusderive their 
parasites. 
Besides the parasitic worms there are also many internal parasites that 
belong to the Protozoa. 
The external parasites of fishes are also numerous. They are chiefly 
crustacea and leeches. 
Among the Crustacea there are a few species of Amphipods that are 
parasitic. One of these, Laphystius sturionis, lives upon the gills of 
fishes and upon the surface of the body. It was found on the gills of 
the ‘ goose-fish,” (Lophius,) in Vineyard Sound, and on the back of 
skates at Eastport. It is remarkable in having large claws developed 
on the third and fourth pairs of legs, those of the first and second be- 
ing small. Its color is light red. 
Certain Isopod crustacea, belonging to the genus Livoneca (Plate VI 
fig. 29) and allied genera, live in the mouths and on the gills of fishes, 
clinging firmly to the membrane of the roof of the mouth, or other 
parts, by means of their strong sharp claws. These are generally 
unsymmetrical inform. The species of the genus Bopyrus live on the 
gills, under the carapax of shrimp and other crustacea, producing large 
tumors. A species is common on species of Hippolytein the Bay of 
Fundy; and a species has been found in this region. The genus Cepon 
is allied to the last, and our species occurs under the carapax of the 
“fiddler-crabs ” in this region. 
Among the Entomostraca the number of parasitic species is still 
greater, but most of these live on the external surface and gills of fishes, 
though some of them occur also in the mouth. The species of Panda- 
rus and allied genera adhere firmly to the skin, and are provided with a 
proboscis. They are very common on sharks, but occur also on other 
fishes. A Faunéaru( te VII, fig. 31) and Nogagus Latreillti (Plate 
VII, fig. 32) were both found on “ Atwood’s shark,” the “ man-eater” of 
this region, associated also with Nogagus tenax. The species of “Noga- 
gus” are merely the males ot other genera, for no one has yet deter- 
mined both males and females ot the various species. The young of 
one species, Caligus rapax, were found swimming free at the surface. 
The species of Argulus and allied genera are less strictly parasitic, or 
rather they adhere less closely, and apparently leave the fishes at pleas- 
