G.-NOTES ON ENTOZOA OF MARINE FISHES, WITH DESCRIP- 
TIONS OF NEW SPECIES. 
RART III. 
AOANTHOCEPHALA. 
By Edwin Linton, ph. d., 
Professor of Zoology in Washington and Jefferson College. 
INTRODUCTORY NOTE. 
The specimens which furnish the basis of the following notes were col- 
lected, for the most part, at the laboratory of the U. S. Fish Commission, 
Wood’s Holl, Massachusetts, in the summers of 1886, 1887, and 1888. 
So far as my observation extends, the only fishes that are much in- 
fested by the Acanthocephala are the striped bass (Roccus lineatus) and 
the flounders. In the latter I have found them abundant only in the 
common flatfish or mud dab ( Pseudopleuronectes americanus). Even in 
the flatfish the occurrence of this parasite is by no means universal. I 
have often examined a lot of a dozen or more of these flounders aud 
found Echinorhynchi in but two or three of them. A peculiarity of the 
Echinorhynchus (E. acus) of this flounder, however, is that when it 
does occur it is apt to infest the host in immense numbers. It is not 
an uncommon thing to find several hundred in a single host. 
The striped bass is very commonly infested with E. proteus, and often 
with great numbers of this parasite. With these two exceptions I have 
found these entozoa of rather infrequent occurrence. The Selachians 
appear to be nearly exempt from them. In a former paper* I recorded 
E. agilis from the dusky shark ( Garcharhinus obscurus ), and in this paper 
a doubtful species from the sand shark ( Carcharias littoralis). In each 
case there was but a single specimen. It may be observed with regard 
to the finding of entozoa in unlooked-for positions, that specimens may 
pass into the alimentary canal in the adult condition along with the 
proper host, and continue to live for some time within what is not the 
proper final host. 
Nearly all the specimens which I have found in the body-cavities 
* Report of Commissioner of Fish aud Fisheries for 1886. 
523 
