SOME PARASITES OF SAGITTA BIPUNCTATA. 205 
long bristles placed at regular intervals and giving it the appearance of 
an annelid. The tail is an efficient swimming organ, and the bristles no 
doubt serve for keeping the whole animal floating. Two large kidney- 
shaped black eyes are conspicuous, the oral sucker has the typical Pharyn- 
gora form which is more like a pharynx in shape, the true pharynx 
leading from it to a short cesophagus and intestinal coeca reaching to the 
end of the body. The whole body is covered with small spines. In the 
specimens inside Sagitta the eyes have begun to show diffuse pigment as 
in the older specimens instead of its being in a thick black mass as in 
the free-swimming form. 
Neither Derogenes varicus nor Pharyngora bacillaris have been 
found encysted, and it is presumed that the encysted stage is 
omitted as the cercarize develop in Sagittt and the other hosts 
into a late form which is ready to enter its final host. The first 
host which presumably is a mollusk is yet to be discovered for both 
of these trematodes. 
Two larval cestodes were also found in Sagitta from the Sound, one 
with four suckers and one with none. These were not identified. It is 
evident that we have in Sagitta an exceptionally good host for many 
parasites, and probably further investigation would be amply repaid. 
LITERATURE. 
1851. Busco, W. ‘“ Beobacht, iiber Anat. und Entwickl. Wirbelloser 
Seethiere,” Berlin, p. 98. 
1879. GreEF, R. “Die Hchiuren.” Nova Acta der Ksl. Leop. Carl. 
Deutschen Akad. d. Naturf. XLI., Pt. II, No. 1. 
1916. Lespour, M. V. ‘“‘ Medusz as Hosts for Trematodes.” J. M. B. A., 
Vol. XI, No. 1. 
1858. Leuckart, R. unD PaGENsTEcHER, A. “‘ Untersuchungen iiber 
niedere Seethiere.” Miiller’s Archiv., p. 559. 
1881. Levinsen, G M. R. “ Bidrag til Kundskab om Grénlands 
Trematodfauna.” Over. K. D. Videns. Selsk. Forh., p. 80. 
1910. Nicott, W. “ On the Entozoa of Fishes from the Firth of Clyde.” 
Parasitology, Vol. III, No. 3. 
1914. Nicott, W. “The Trematode Parasites of Fishes from the 
English Channel.” J.M.B.A., Vol. X, No. 3. 
1906. OpHNER, T. “ Die Trematoden des Arktischen Gebietes.”” Fauna 
Arctica. 
