AMERICAN PARASITIC COPEPODA. 251 
although proportionately smaller, have all the specific characteristics 
of the female. The antennule (Fig. 7) are slenderer, and the 
internal bristles of the basal joints more distinct, while the hooks on 
the external rami of the antenne are simple, and do not present the 
toothed sickle-shaped form observable in the female. The strengthen- 
ing chitinous plates (ch., Fig. 7) are also of different form. The 
mandibles and maxillze seem only to differ in size. 
The peculiar form of the first maxillipedes described by V. Nord- 
mann for A. percarwm can also be seen here. The deep and narrow 
sternum of these appendages (Fig. 8), shaped somewhat like a dice 
box, gives origin to the powerful adductor muscles, which occupy 
the greater part of the cavities of the basal joints. Of the two 
muscles which move the terminal claw-like joint, the flexor is much 
the more powerful, and keeps the claw shut against the toothed 
chitinous outgrowth of the basal joint. 
The second maxillipedes (Figs. 6 and 9) are two-jointed, the 
distal joint terminating in two claws, both of which are hinged to it, 
and which are anterior and posterior in position. The anterior 
shuts into the posterior, which is hollowed out to receive it. The 
basal joint is strengthened by a diagonal chitinous bar: it is to this 
that V. Nordmann refers as a “ muscle of almost cartilaginous con- 
sistence.” The basal joints abut against each other in the middle 
line, and give rise to a cylindrical structure, which forms a striking 
feature in the profile view of the male (Fig. 6). This is represented 
from the ventral aspect in Fig. 9, in which an evident orifice may 
be seen. This may possibly be the outlet of certain little glandular 
masses situated in the basal joints of the appendages (g/., Fig. 9), 
but the want of fresh specimens has hindered a satisfactory 
elucidation of this organ. The glands may possibly be homologous 
with the arm glands of the female: whether their secretion is 
employed for the fixation of the male on the female I have not deter- 
mined. A thorough examination of the male reproductive apparatus 
of the Lernzeopodide is very desirable for the purpose of elucidating 
the formation of the spermatophores in the Parasitic Copepoda, as 
Gruber has recently done for the Free forms.’ I regret that my 
alcoholic specimens have not permitted an exhaustive study of this 
point. 
1 Zeit. wiss. Zool. B, XXXII. 
