THE CEPHALOPODA 311 



has disappeared, the anterior extremities of the capsules of the 

 branchial hearts communicate with the kidneys (Fig. 278, r.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 



v.n 



A 



ev 



Heart, kidneys, and gills of Spirilla, ventral aspect. a.n, anterior aorta; ab.v, abdominal 

 vein; a.p, branchial heart-appendage; o.r, afferent branchial vessel; ou, heart-auricle; b.h, 

 branchial heart ; b.n, branchial nerve ; e.v, efferent branchial vessel ; g, gill ; g.a, genital artery ; 

 7, junction of the visceral nerves ; 7, - , kidneys : fc.o, kidneys opening ; p.a, pallial arteries ; p.v, 

 pallial vein ; r.p, reno-pericardial opening ; s.b, spongy renal glandular bodies ; v.c, vena cava ; 

 ven, heart- ventricle : v.n, 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, k). 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, r.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, .?), 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 



