386 



COMPARATIVE ANATOMY. 



tlie body, is attached to tins organ ; it may be directly continuous 

 with the copulatory organ, and forms a groove which reaches to it 

 (Dolium, Harpa, Strombus), or it may traverse the penis in the form 

 of a canal (Buccinum, Littorina, Paludina). 



§ 298. 



The sexes are quite separate in all the Cephalopoda. The male 

 and female organs greatly resemble one another in their general 

 mode of arrangement; the most essential point in which is that 



the germ-glands are not directly continuous 

 with their efferent ducts. This fact is of 

 importance, as it seems to point to the 

 use of an organ which primitively did 

 not belong to the generative appara- 

 tus. In any case, this arrangement is alto- 

 gether different to that seen in the germ- 

 glands of the Gastropoda and Pteropoda, 

 where the secreting portions of the glands 

 gradually pass into the efferent ducts (cf. 

 supra, § 292). In the Tetrabranchiata the 

 efferent ducts are not perfectly continuous. 

 The oviduct and sperm-duct both lead into a 

 wider cavity, from which these ducts start 

 again. 



Of the female organs, the ovary is formed 

 by a lobate gland, which is invested by a 

 special sac, with which it is connected at one 

 point only. The duct (oviduct) is, as a rule, 

 single. In the Octopoda and in Loligo sagit- 

 tata it is double (Fig. 199, od od), a fact which 

 points to its having been primitively double ; 

 iu the rest — as also in Nautilus — this double 

 character has disappeared owing to the 

 atrophy of one of the oviducts. The oviduct 

 is attached to the covering of the ovary, so 

 that the ova only reach the duct by passing 

 through the space enclosed by this covering. The oviduct ordinarily 

 opens at the commencement of the funnel ; it only opens some way 

 back in the branchial cavity in those forms in which the male has a 

 copulatory arm ; hectocotylism is the cause therefore of a functional 

 adaptation. At one point the oviduct has a pad-like circular invest- 

 ment of glands, formed by tubes set radially to the axis of the 

 oviduct (Octopoda). In Nautilus, there is a larger number of these 

 glands, and they extend almost as far as the opening of the duct. 

 Where these glandular organs are absent their place is taken by a 

 secreting apparatus placed close to the opening. 



A pair of so-called " nidamental glands" are the accessory 

 organs of the female apparatus ; they consist of elongated lamellar 



Fig. 205. Male genera- 

 tive organs of Octopus. 

 If Testis, c Its capsule. 

 re Efferent duct, ve' En- 

 largement, which serves 

 as a seminal vesicle, g Ac- 

 cessory glands. bN Need- 

 ham's Pouch (after Cams 

 and D' Alton). 



