632 LECTURE XXIV. 



made out : the other modifications of the arm relate exclusively to 

 the impregnating function assigned to it. 



One presumes that, in the coitus, the arms of the two sexes being 

 mutually interlaced, as described by Aristotle, the expanded recepta- 

 cular end of the modified arm, with the spermatozoa, is introduced 

 into the funnel of the female : but with whatever part of her surface 

 the masculine arm comes into contact, it adheres thereto forcibly by 

 means of the double close-set row of large suckers. In the violent act 

 of termination of the embrace, whether through alarm or other cause, 

 the modified arm is snapped off and left adhering to the female by the 

 suckers, where it long retains the power of motion. Such is the con- 

 clusion of the long-mooted questions of the Argonaut, its shell, the 

 Jse of the brachial membranes or " sails," and the true sexual dis- 

 tinctions of the male and female. 



The female organs consist in the Dibranchiate Cephalopods, as in 

 the Nautilus, of an ovarium, oviduct, and, usually, nidamental glands, 

 but with several modifications in the efferent part of the apparatus. 

 The ovary is always single, of a round or oblong form, longest and 

 narrowest in Loligo sagittata ; it is a sac with a serous and a firm 

 fibrous tunic : the ovisacs {JiQ' 230, a, a), formed of a thin membrane 

 derived from the general sac, are usually of an elliptical form and 

 seem reticulate by the characteristic folding of the vitelline tunic of 

 the ovum appearing through the transparent membrane : they are 

 attached to one part of the ovarian cavity, as in the Nautilus. The 

 ova and ovisacs are proportionally larger in the Decapods than the 

 Octopods ; are largest in Sepiola, smallest in Argonauta. In the 

 Octopods there is a communication between the ovarian sac and 

 the aquiferous pericardial cavities which open into the branchial 

 chamber. 



In Sepia, Sepiola, Rossia, and Loligo vulgaris, there is a single 

 oviduct, with a glandular laminated outlet ; and there are two distinct 

 laminated nidamental glands on each side of its termination. In the 

 Octopods there are two oviducts, which in Argonauta and Trem- 

 octopus are simple ; but in Octopus and Eledone are each provided 

 with a special glandular enlargement about the middle of their 

 course : there are no detached nidamental glands. In Loligo sagit- 

 tata and Onychoteuthis there are two distinct convoluted oviducts, 

 and two separate nidamental glands. These glands in the Cuttle- 

 fish rest upon a soft parenchymatous body, of a bright orange colour : 

 the corresponding part is rose-coloured in Sepiola : it is double in 

 Rossia (^g. 230, i, i), and the Calamaries : these bodies have no 

 ducts, and appear to be the homologues of the suprarenal bodies in 

 the vertebrate animals. 



