CEPHALOPODA. 



557 



length of the glandular part of the oviduct is 

 one inch ; its termination is at the base of the 

 funnel close to the anus, and immediately 

 behind an accessory glandular apparatus. 



This body is analogous to the laminated 

 ovarian gland of the Pectinibranchiate Tes- 

 tacea, and, as in them, forms no part of the 

 oviduct ; but in the Nautilus it is extended in 

 the transverse direction, and composed of two 

 lateral convex symmetrical masses, resem- 

 bling the corresponding separate symmetrical 

 glands in the Decapoda, but which are here 

 united by a third middle transverse series 

 of laminae. All the laminae are deep, pec- 

 tinated, and close-set, and are supplied by 

 a large artery. The lateral groups form 

 conspicuous projections on the external sur- 

 face of the ventral aspect of the Nautilus, 

 and are covered internally by a layer of thin 

 tough membrane ; the middle laminse are 

 exposed. 



The female organs of the Dibranchiate Ce- 

 phalopods present different structures, as be- 

 fore observed, in the Decapodous and Octo- 

 podous tribes. In the former the oviduct or 

 oviducts have laminated glandular termina- 

 tions, near to which are placed two detached 

 nidamental glands: in the latter there are al- 

 ways two distinct oviducts which pass through 

 laminated glands, but there are no detached 

 superadded glandular organs. 



The Sepia, among the Decapodous Cephalo- 

 pods, manifests in its generative, as in its 

 prehensory and testaceous organs, a near affinity 

 to the Tetrabranchiate order, while the form 

 of the female apparatus in the Octopods more 

 closely corresponds, on the other hand, with 

 the same parts in the Oviparous Cartilaginous 

 Fishes. The ovarium in both tribes is a single 

 organ, situated at the bottom of the pallial sac, 

 and consisting of a capsule and ovisacs di- 

 versely attached to its internal surface. 



The ovisacs are proportionally larger in the 

 Decapods than in the Octopods. In the 

 Cuttle-fish they are extremely numerous, and 

 are appended by long and slender pedicles to 

 a longitudinal fold of membrane extending 

 into the ovarian cavity, from the dorsal aspect 

 of the sac. The plicae of the internal glan- 

 dular surface of the ovisacs or calyces are 

 disposed in a reticulate manner, forming cor- 

 responding light-coloured opake lines on the 

 external surface, which, being contrasted against 

 the dark-brown tint of the contained ovum 

 shining through the transparent areolar space, 

 occasions the beautiful and characteristic ex- 

 terior reticulate markings of the undischarged 

 ovisacs. 



In the Genus Rossia, from which the sub- 

 joined illustration of the Decapodous type 

 of the female organs is taken (Jig. 239), the 

 ovisacs have the same structure and mode 

 of attachment as in Sepia, but they are rela- 

 tively of double the size and fewer in num- 

 ber. In the specimen which we dissected, 

 we found the greater part of the ovisacs con- 

 taining the ovum in various stages of deve- 

 lopment, as at a, a. One was in the act of 

 shedding the ovum, as at b, f; others were 



Fig. 239. 



a 



Female generative Organs, Rossia palpebrosa. 

 (Natural size.) 



discharged, collapsed, and shrivelled, and in 

 progress of absorption, as at c, c. The pa- 

 rietes of the ovarium consist of a thin and 

 almost transparent membrane, which is con- 

 tinued forwards to form the oviduct (</, </). 

 This canal commences in the Cuttle-fish by a 

 round aperture, about a third of an inch in 

 diameter, immediately beyond which it dilates, 

 and continues forwards of the same thin and 

 membranous structure to within an inch of its 

 extremity, where, as in the Nautilus, its pa- 

 rietes are suddenly thickened by the develop- 

 ment of a number of broad, close-set, glan- 

 dular laminae. The chief difference between 

 the Sepia and the Nautilus obtains in the greater 

 extent of the membranous part* of the oviduct 

 in the former. 



In the Rossia the oviduct (o?) differs only in 

 greater relative width : the terminal gland (e) 

 is composed of two lateral semioval groups 

 of transverse glandular lamellae, each group 

 being divided by a middle longitudinal groove; 

 the oviduct was contracted immediately before 

 opening into the interspace of the glands, and 

 a deep but narrow groove, which is probably 

 dilated during the passage of the ova, was 

 continued between the two groups of lamellae 

 to the termination of the oviduct. This was 

 situated towards the left side and behind the 

 orifices of the nidamental glands. 



The female organs of the Sepiola present the 



* In the original description of the Nautilus, this 

 membranous part of the oviduct was regarded, 

 from its brief extent, and the sudden commence- 

 ment of the glandular tunic, as a connecting process 

 of the peritoneum ; it was accurately represented, 

 however, in the figure, (pi. viii. Jig. 9.) 



