252 AMERICAN PARASITIC COPEPODA. 
Fig. 10 represents the abdomen of the male from the ventral 
surface, and is intended to illustrate the position of the male repro- 
ductive organs. The testes occupy the anterior segment of the 
abdomen, and the Ist portion of the vas deferens is dilated by the 
accumulated seminal elements. The 2nd portion is convoluted and 
beset with glandular tissue, till it opens into the pocket containing 
_ the spermatophore in course of formation. The ripe spermatophore 
may be studied in Fig. 11. No indication of the canal or capsule 
with which the spermatophore is attached to the female can be seen 
at this stage. The case of the spermatophore passes by a neck-like 
constriction into the case of the developing spermatophore, and it is 
through the aperture formed by the rupture of this constriction that 
the contents pass out. These correspond to the three elements 
described by Gruber for the Free Copepoda, viz., a globular central 
mass, ‘(085 mm. in diameter, representing the axial cement in the 
free forms, numbers of rod-like spermatozoa (not more than 2, in 
length), occupying the greater part of the rest of the axis of the 
spermatophore, and lastly, the refractive polygonal discharging 
corpuscles (the Austreibemasse of German Zoologists). 
These I have only observed in preparations taken from alcoholic 
specimens of the male, and I have not had the opportunity of study- 
ing the mode of fixation of the spermatophore on the female. Two 
kinds of cement have been described in the Free Copepoda, (1) that 
situated in the spermatophoral dilation of the vas deferens, which 
serves to fix the ejected spermatophore to the female, and (2) 
that in the axis of the spermatophore, and which in Canthocamptus, 
e.g., forms a curved canal through which the spermatozoa are ejected. 
That the former kind of cement exists also in Achtheres is readily 
seen from the pieces of it adhering to the post-abdomen of the 
female, and which I have referred to above as being often present in 
considerable quantity. It appears to be formed by the glands grouped 
round the lower part of the vas deferens. The second sort of 
cement is ejected from the spermatophore in the form of a somewhat 
globular mass, composed of a peripheral translucent layer with finely 
granular contents. It appears to me that this mass undergoes a 
change similar to what takes place in Canthocamptus only more 
complicated, viz., that after the fixation of the spermatophore to the 
1 Gruber Zeit, wiss, Zool. 32, Pl. 25, Fig. 15. 
