241 
tions. Testes elliptical, usually contiguous. Cement gland a single syn- 
cytial mass containing relatively few giant nuclei. 
The giant nuclei furnish the most easily available characters for the 
recognition of members of this family. Subcuticular nuclei in members 
of the other families of Acanthocephala show a considerable degree of 
variability in size and in form, but in no case do they approach the con- 
dition found in this family. The dendritic nuclei of Echinorhynchus 
thecatus Linton are relatively difficult to demonstrate. In addition they 
differ so broadly from the form of the giant nuclei of the Neoechino- 
rhynchidae that no confusion of the two is possible. The subcuticular 
nuclei are especially conspicuous in the Neoechinorhynchidae. Their loca- 
tion is clearly discernible as pronounced elevations of the body-surface 
both in living individuals and in preseryed specimens even before stain- 
ing. The number found in the subcuticula so far has been absolutely con- 
stant for every individual of the family examined, but their relative posi- 
tion within the dorsal and ventral lines of the body is subject to slight 
individual variability even within the confines of a given species. For 
example, the single nucleus of the mid-ventral line does not always bear 
a fixed relationship to the nuclei of the mid-dorsal line, but may be 
directly opposite the second dorsal nucleus or slightly anterior or pos- 
terior to it. The ratio of the spacing between the dorsal nuclei and the 
body-length is apparently an inconstant one. 
The giant nuclei of the lemnisci are apparently constant both in num- 
ber and in arrangement for all members of the family. In the examina- 
tion of several hundred: individuals, representing all the different genera, 
in every instance where conditions permitted close observation one lem- 
niscus showed two giant nuclei while the other bore but a single one. 
The cement gland of Neoechinorhynchidae shows considerable vari- 
ation in the number of giant nuclei even within the confines of a single 
genus; but within species limits the number of nuclei in this gland is 
absolutely fixed. Bieler has found eight in the cement gland of N. agilis 
and twelve in that of N.rutili. As to Amercian species of Neoechino- 
rhynchus, the writer has found eight giant nuclei in the cement gland of 
N. cylindratus, of N. emydis, of N. tenellus, and of N. crassus. In Tanao- 
rhamphus longirostris there are sixteen giant nuclei in the cement gland, 
while in Gracilisentis and in Octospinifer there are only eight. 
The. shape of the proboscis and the shape and number of the 
proboscis-hooks and their roots afford the most readily available charac- 
ters for the separation of the genera of this family. 
Synopsis or NortH AMBRICAN GENERA AND SPECIES 
NEOECHINORHYNCHUS Stiles and Hassall, 1905, sens. str. 
Neorhynchus Hamann, 1892, preoccupied. 
Eorhynchus Van Cleave, 1914. 
Echinorhynchus Zoega, 1776, in part. 
Generic Diagnosis—Neoechinorhynchidae with short, globose pro- 
boscis armed with three circles of six hooks each. Terminal hooks con- 
