786 



/( x )LOGY 



SECT. 



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

 four afferent branchial veins (Fig. 683 a.l.aff, P-Luff, P- r - a f 

 r.ant. aff.) 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 afferen 

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

 Each renal sac (/. neph. s., r. neph. s., I. post. neph. s., r. post. neph. s. 

 opens into the mantle-cavity, as already stated, by an orific 

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

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



I.V.O.J3 

 l.posl.nepli'.a.p 



r.pcst.nefih.afi 



FIG. 683.: 



r.post-.ne-ph.s 



. 688. Nautilus pompilius, 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. 1. aff. left oral afferent vessel ; cten. right cteuidia ; I. neph. s. left nephridial sac ; 

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

 aperture ; 1. post. neph. s. left aboral nephridial sac ; l.v.ap, left viscero-pericardial aperture ; 

 p. I. aff. left abortil afferent vessel ; p. r. o.ff. right aboral afferent vessel ; r. ant. ajfr. right 

 oral afferent vessel ; r. ant. aur. right oral auricle; ren. app. renal appendages; r.neph.ap. 

 right nephridial aperture ; 7-. post. aur. right aboral auricle ; r. poxt. neph. s. right aboral 

 nephridial sac ; r. v. ap. right viscero-pericardial aperture ; ven. c. vena cava ; cent, ventricle ; 

 vise. per. s. viscero-pericardial 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. 



