AND THE MALES OF CERTAIN CEPHALOPODS. 141 



the anterior extremity of the sac, where the beak-Hke projection 

 of the spermatophore commences. In fact, the cord becomes 

 very delicate (PL IV. fig. 3 a), and finally attaches itself to the 

 posterior extremity of the ejaculatory canal, which in its turn 

 fills the beak-like projection of the spermatophore. This eja- 

 culatory canal is formed by a very firm tube with thick pa- 

 rietes, having only a very small canal in its interior. Its parietes 

 are excessively transparent, resist pressure greatly, and do not 

 become disfigured by the action of water. We have been quite 

 unable to discover any further structure in this homogeneous 

 tube, which commences in the sac of the spermatophore by a 

 rounded extremity, slightly drawn out, and having a minute 

 aperture into which the extremity of the axis of the spermatic 

 cord penetrates as a very fine thread repeatedly folded up in the 

 cavity of the ejaculatory canal. The latter widens very soon, 

 together with its internal cavity, which is filled in the whole 

 length of its course by a spirally folded membranous ligament. 

 We see distinctly in the posterior extremity of the ejaculatory 

 cord the commencement of this membrane, which clothes the in- 

 terior of the canal of the cord, and seems at first plaited into a 

 number of transverse folds, which by degrees assume a spiral 

 disposition, so that at last the end of the ejaculatory canal re- 

 sembles under the microscope the intestine of a shark with its 

 spiral valve (PI. IV. fig. 4.). The ejaculatory canal forms at first 

 many folds in the wider portion of the beak-like prolongation ; 

 after which it becomes continued almost in a straight line, form- 

 ing itself the axis of the prolongation. At the extremity of this 

 prolongation may be distinguished the whole external envelope 

 of the spermatophore, which becomes bent back, so to say, to- 

 wards the interior to form the tube of the ejaculatory cord, whose 

 canal, clothed by the spiral membrane, is continued as far as 

 this extremity. 



The analogy between the structure of the spermatophore which 

 we have just described and that of those of the other Cephalo- 

 poda with which we have long been acquainted is evident, so 

 that we need insist at no greater length upon this point. The 

 envelope which swells out by the action of water ; the ejacidatory 

 cord, with its internal spiral ligament; in all these points the 

 resemblance is complete, with this difference only, that the semi- 



