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portions of the copulatory bursa. Its length is about 0,045 mm. In side 
view the sperm reservoir is a triangular sac whose size varies radically 
under different conditions of sexual activity. 
A single shad taken from the Illinois River at Havana, Illinois, 
July 4, 1910, gave three immature females each having a single 
ovary. In size these oval masses varied from 0,065 0,038 mm. to 
0,110 X 0,078 mm. In a mature female containing both egg-masses and 
embryos several of the former were found to measure 0,110 X 0,049 mm., 
though they may vary enormously even within the same individual. The 
tract through which the developing embryos are discharged has a length 
of 0,490 mm. from the anterior end of the selective apparatus to the 
genital orifice. Of this tract 0,127 mm. is occupied by the vagina, which’ 
in the region of the vaginal sphincter has a diameter of 0,045 mm. The 
genital orifice already referred to lies on the ventral surface of the body 
near the posterior end. 
Dorosoma cepedianum (Le Sueur) taken from the Illinois River at 
Havana, Illinois, occasionally carried this worm in its intestine. Mature 
forms have been taken during the months of June, July, November, and 
December, while a few individuals taken in July were still immature. 
Ordinarily this species was represented by a few scattering individuals 
occurring in the same host with the much more numerous N. gracilisentis. 
The periods of infestation of these two species of parasites in Doro- 
soma are not coincident. A comparison of the two forms reveals the 
fact that while no specimens of the more common species have ever been 
taken in the summer months, the species just described evidently reaches 
a maximum at that time. But a very small percent of the shad exa- 
mined during the past three years have borne an infestation of Neo- 
rhynchus longirostris. | 
Neorhynchus emydis (Leidy). 
Syn. Echinorhynchus emydis Leidy 1852. — Echinorhynchus hamulatus Leidy 1857. 
This species originally described by Leidy in 1852 was later (1857) 
referred to by him under a new name, £. hamulatus. Through the 
efforts of Professor Ward the writer was permitted to study specimens 
of this species contained in the Leidy collections of the Academy of 
Natural Sciences of Philadelphia. The writer will here supplement the 
incomplete original description with facts gained from a study of the 
material from Leidy’s collection and of large numbers of the same 
species in his own collection. 
Body very much elongated, cylindrical. Females 10—32 mm. long, 
average maximum width 0,70 mm. Males about 8—11 mm. long by 
0,70 mm. wide. Proboscis globular, length usually equals breadth, 
