CEPHALOPODA. 463 



between them (Sepia), or fused into one as in the majority, e. g. Loligo. 

 The walls of these sacs are covered by a more or less flattened epithelium, 

 except at the spot where they are in contact with the branchial arteries. 

 The latter here give off a number of caecal and branched venous 

 appendages. The nephridial epithelium coating these vascular tufts is 

 columnar and longitudinally striated, its surface covered with a slimy 

 secretion, in which reddish-coloured crystals, also occurring loose in the sac, 

 are commonly found, as well as greenish- coloured spheres. Crystals and 

 spheres alike appear to be excretory products \ Vascular tufts of a similar 

 character are given off by the branchial arteries of Nautilus into the viscero- 

 pericardial sac. The pericardial gland appended to the branchial hearts 

 (supra] in Dibranchiata appears to be a structure of excretory character. It 

 is a somewhat conical body, which contains a number of caeca communi- 

 cating by one (Sepia) or several (Eledone} slits with the viscero-pericardial 

 sac, and lined by an epithelium continuous with that of the sac. At the 

 bases of the caeca the epithelium becomes glandular. 



The sexes are separate. ' The single testis and ovary are formed from 

 the walls of that part of the viscero-pericardial sac or secondary coelome in 

 which they lie, and from which the ciliated ducts are prolonged to the 

 exterior. The left duct is rudimentary in both sexes in Nautilus ; there 

 are two ducts in the male Eledone moschata (Octopoda}, and the female of 

 Omtnastrephes (Decapoda), and of Octopoda, except Cirrhoteuthis, whereas in 

 other instances there is but one duct, that of the left side. The vas deferens 

 has a widened glandular section, and bears an accessory gland, and near its 

 termination a large sac, Needham's sac, in which the spermatophores are 

 contained. It ends in a papilla, which may be of great extent, in Octopoda. 

 The spermatophores are cylindrical bodies of some length and complicated 

 structure, containing not only sperm but an exploding substance as well. 

 The oviduct in Octopoda has as a rule a dilated portion (present but uni- 

 lateral in Nautilus) with walls produced into glandular leaflets, forming an 

 albumen gland. In Decapoda a similar gland opens into the end of the 

 oviduct. The oviduct, like the vas deferens, opens between the anus and 

 nephridial aperture. Nautilus possesses a nidamental gland, situated on 

 the mantle, the Decapoda a pair of such glands, in both cases composed of 

 lamellae. A third gland, composed of coiled tubes, is present in most 

 female Decapoda. 



With the exception of a few Dibranchiata (e. g. Ommastrephes\ a 

 remarkable change affects one of the arms in the male. It is enlarged 

 either at its apex or base, and the suckers of the enlarged portion obliterated. 



1 Solger found that sulph-indigotate of soda ( = indigo carmine) when injected under the skin of 

 an Eledone moschata made its appearance in this excretory epithelium as well as in solution in the 

 cavities of the nephridia. Cf. Z. A. iv. 1881. Injection of the same substance into the blood of 

 Mammalia is followed by its excretion in the kidney and the liver. 



