LHE CEPHALOPODA 311 
has disappeared, the anterior extremities of the capsules of the 
branchial hearts communicate with the kidneys (Fig. 278, 7.p). 
The renal capsules are thin-walled and somewhat voluminous 
sacs in all the Cephalopoda. In Nautilus they are four in number, are 
ventral and superficial, and have no communication with one another 
or, as has been explained, with the pericardium. Each of the four 
capsules has its own simple slit-like orifice (Figs. 275 and 276, 
neph.a, neph.p), and each contains a small portion of the glandular 
appendages of the afferent branchial vessels, the appendages being 
formed by ramifications of these same vessels, covered by an 
excretory renal epithelium. The appendages situated on the other 
Heart, kidneys, and gills of Spirula, ventral aspect. @.a, anterior aorta; ab. v, abdominal 
vein; a.p, branchial heart-appendage ; a.v, afferent branchial vessel; au, heart-auricle ; b.h, 
branchial heart ; b.n, branchial nerve ; e.v, efferent branchial vessel ; g, gill; g.a, genital artery ; 
Jj, junction of the visceral nerves; k, kidneys; k.o, kidneys opening ; p.a, pallial arteries ; p.v, 
pallial vein ; 7.p, reno-pericardial opening ; s.b, spongy renal glandular bodies ; v.c, vena cava ; 
ven, heart-ventricle: v.2, visceral nerve. (After Huxley and Pelseneer.) 
side of these vessels, in the pericardial coelom, are also excretory 
organs, and constitute the pericardial glands. 
In the Dibranchia there are two renal capsules, also ventral and 
superficial ; these two kidneys are attached to one another in the 
median line in the Octopoda, and they communicate to a greater or 
less extent with one another in the Decapoda, with the exception of 
Spirula (Fig. 277, &). In the majority of the Decapoda the renal sacs 
extend as far as the lower surface of the shell, on the anterior or 
physiologically dorsal side, and are traversed in this region by the 
hepatic ducts. Each contains one of the two divisions of the vena 
cava (Fig. 273, 7.s.v.c, r.d.v.c) as well as the terminal part of the 
abdominal vein. All these vascular trunks are covered by spongy 
glandular appendages (Fig. 273, a.r), whose structure is similar to 
that of the corresponding parts of the renal organs of Nautilus; these 
appendages constitute the secretory portion of the kidneys. The 
external orifices of the renal sacs of the Dibranchia are situated 
