PARASITES OF FISHES OF THE WOODS HOLE REGION. 
439 
Many spherical bodies with concentric structure were noted in the contents of the excretory 
vessels. The largest of these measured 0.016 mm. in diameter (7, p. 288). 
While watching a living specimen a curious phenomenon was observed in the vicinity of the 
shell gland. A fine hair-like body which lay in several coils appeared to be turning rather rapidly 
around a central space. A somewhat similar appearance was present in two smaller spaces nearby. 
The specimen, while still living, had been partly stiffened by holding the compressor over the flame 
of an alcohol lamp for a few seconds. This phenomenon evidently has something to do with the 
formation of the eggshell, but just what I could not make out. 
Pomolobus pseudoliareng'us, Alewife. 
FOOD. 
Only young have been examined. Thirty-six were examined in July and August, 1899, on five 
different occasions. In all of them the alimentary canal contained copepods, sometimes in enormous 
numbers. In the summer of 1900 (July 9 and August 10) fourteen specimens were examined, and 
in addition to copepods young squid and large numbers of small shrimp were found. These specimens 
were taken at Wareham and were larger than the fish examined the year before. About the same 
entozoa are found in the young alewife as in the young herring, with which they are associated. 
NEMATODES. 
1. Nematodes, immature. A few found in one lot in 1899 (Aug. 15). 
CESTODES. 
2. Larval cestodes ( Scolex polymorplius Dujardin). Free in intestine. Aug. 3, 1899. For account of 
similar forms, see 4, 789-792. 
TREMATODES. 
Obtained by washing out the alimentary canal and decanting the material. 
3. Distomum appendiculatum Rudolphi. Found on all occasions in 1899, usually numerous. Aug. 10, 
1900; verjr numerous. See 7,p. 289, pi. xxxvi, figs. 25, 26. Measurements of living specimens 
in one lot, 1.28 mm. to 2.56 mm. 
4. Distomum mtdlomm Linton. See 7, p. 290, pi. xxxvn, figs. 38, 39; also under Clupea harengus, No. 6. 
5. Distomum bothryophoron Olsson (?). [PI. xxxn, figs. 355, 356.] See under Clupea harengus, No. 7. 
Aug. 2, 3, and 19, 1899; very few. 
Body smooth, short, fusiform; neck conical; tail tapers to a point. Oral sucker nearly circular 
in ventral view, aperture broadly triangular; pharynx subglobular, close to oral sucker; oesophagus, 
none; rami of intestines simple, extending nearly to posterior end. Acetabulum in middle of body, 
prominent, about twice the diameter of the oral sucker, aperture transverse. Testes two, rather small, 
oval-elliptical, immediately behind the acetabulum. Ovary behind testes. Exact position not clearly 
determined. Vitellaria a single six or seven lobed mass, lying laterally toward the posterior end. 
Ova small, elliptical, very numerous, filling all of body back of acetabulum. Reproductive aperture 
in front of acetabulum, on median line. Dimensions in millimeters of specimen in glycerine: Length, 
0.8; diameter of body, anterior 0.1, middle 0.3, posterior 0.03; diameter of oral sucker 0.1, of 
acetabulum 0.3; testes, 0.07 and 0.05 in two principal diameters; pharynx, length 0.05, depth 0.07; 
ova, 0.017 and 0.010 in the two principal diameters. These measurements were made from ventral 
view, except the pharynx, which was measured in lateral view. 
6. Monostomum sp. [PI. xxxiv, figs. 377-379.] Aug. 19, 1899; 4. Very small, oval or elliptical. 
Dimensions in millimeters: Length, 0.6; diameter, 0.34; diameter of genital acetabulum, 0.07; 
diameter of oral sucker, 0.07; ova, 0.02 and 0.017 in the two principal diameters. Vitellaria in two 
masses lying one on either side of genital acetabulum. Uterus very voluminous; body behind 
acetabulum filled with ova. 
PROTOZOA. 
7. Sporozoa. Aug. 2, 1899; among the muscles of back and side. Of 22 fish 9 were infected. 
Mr. E. E. Tyzzer says that about half of the young alewives examined by him in 1900 have 
these cysts in the flesh, but that they are less common in the larger fish. For fuller account, see 
under Clupea harengus, No. 8. 
