16 Prof. KótLikER on the Structure of 
On the contrary, the male organs were readily traced, and appeared highly 
developed. The testicle presented the same structure as that of the Hectocotyle 
of Tremoctopus, and was inclosed in a large elliptic sac in the dorsal surface, 
just wherethe pigment-cells were placed: it gave origin to a small vas defe- 
rens, which could not be traced to any great length in two of my specimens. 
In the before-mentioned animal, however, in which the end of the appendage 
pierced through an opening in the back, the vas deferens was connected with 
the appendage, and ran closely attached to its superior surface until it reached 
the basis; hence it took its course backwards, and entered there a peculiar long 
tube situated under the sac containing the testicle. "This tube, which is com- 
posed of two membranes, the internal being thick and muscular, the external 
thinner and of a mother-of-pearl lustre, may be regarded as the penis. In its 
interior the vas deferens makes a great many convolutions till it reaches the 
hindermost part of the body, where it opens together with the penis by a small 
orifice. The semen and the spermatozoa resemble those of the Hectocotyle of 
the Tremoctopus. 
Having thus shortly stated the result of my observations on these two spe- 
cies of Hectocotyle, I proceed to the most important part of this essay, that is 
to say, to a statement of the reasons which induce me to regard these Hecto- 
cotyle as the males of the Cephalopods on which they live. 
But first I must prove that the Hectocotyle described are really animals, 
inasmuch as Costa considers one of them as a detached portion of the Argo- 
nauta, or as a part of the seminal apparatus. According to my observations, 
mn can be no doubt of the object in question being a distinct animal, as I 
had it for hours living in my room, and observed its energetic and evidently 
voluntary motions. Neither can the Hectocotyle be a part of the seminal ap- 
paratus, for it is not to be supposed that in that case it would be provided 
with vessels, nerves, muscles, pigment-cells, &c.; nor a detached portion of the 
Cephalopod on which it is found, no injury being observable on the latter, and 
the Hectocotyle always living perfectly free on its surface. i 
As it is therefore placed beyond all doub 
animals, tbe question is reduced to whether 
their Cephalopods,— whether, 
t that the two Hectocotyla: are 
they stand in a nearer relation to 
in fact, they are the males of these Cephalopods, 
