786 



ZOOLOGY 



hsemocoele. At its aboral end it presents a dilatation from which 

 four aprent Ivanchial veins (Fig. 683 a.l.aff, p.l.aff, p.r.aff, 

 r.ant. a/.)— two right and two left — proceed to the corresponding 

 ctenidia, at the bases of which veins from the aboral region join 

 them. There are no branchial hearts. 



The renal organs (Fig. 683) are, like the ctenidia and the afferent 

 and efferent vessels, four in number, instead of two as in Sepia. 

 Each renal sac (I. nepJi. s., r. neph. s., I. post. neph. s., r. piost. neph. s.) 

 opens into the mantle-cavifc}', as already stated, by an orifice 

 which is not drawn out into a tube. There is no communication 

 between the cavities of the different sacs, and thus no median 



l.v.ap 

 L.pust,Tiepfv.a.p 



r pcstne^h.afj 



rpost.n.&ph.s 



7:post.a.ur 



' ■* t.posc.7t.epfv,!i 



l/CSO.pBTZS- 



Fig. 683.— Nautilus pompiliuSj renal sacs, with ctenidia and other related parts, as seen from 

 the posterior aspect ; the "boundaries of the four renal sacs represented by dotted lines. 

 a. I. aff. left oral afferent "vessel ; cten. right ctenidia ; I, neph. s. left nephridial sac ; 

 I. neph. ap. left oral nephridial aperture ; I. post. neph. ap. left aboral nephridial 

 aperture ; I. 'post, neph. s. left aboral nephridial sac ; l.v.o.p, left viscero-peri cardial aperture ; 

 p. I. aff. left aboral afferent vessel; p. r. aff. right aboral afferent vessel ; r. ant. off. right 

 oral afferent vessel ; r. ant. aur. right oral auricle; ren. ajp^. renal appendages; r.neph.a2}. 

 right nephridial aperture ; r, piost. aur. right aboral auricle ; r. post. neph. s. right aboral 

 nephridial sac ; v. v. ap. right viscero-perieardial aperture ; ven. c. vena cava ; vent, ventricle ; 

 vise. per. s. viscero-perieardial sac. 



chamber as in Sepia, and there is also no communication with the 

 pericardium. The cavities are found to contain phosphate of 

 lime. Into each projects, from the corresponding afferent 

 branchial vein, a compact rounded group of venous appendages 

 {ren. app.), consisting of two symmetrical portions. Internal to 

 these, each afferent vein has connected with it a second group of 

 glandular appendages, which are cylindrical or club-like in form ; 

 they project, not into the nephridial sac, but into the peri- 

 cardial compartment of the coelome. They have been compared 

 with the appendages of the branchial heart of Sepia, but differ in 

 their relations to the renal appendages. 



