THE CEPHALOPODA 309 
thence into the respiratory vessels of the branchia for oxygenation 
before it is finally carried to the heart. 
3. Haeretory Apparatus.—The coelom of the Cephalopoda is very 
extensive. It comprises the gonocoele and the pericardial coelom ; 
these cavities communicate freely with one another (Fig. 252, coe) 
and are only separated by an incomplete septum, which is atrophied 
in Sepia. In Nautilus this coelom extends into the aboral region of 
the body and its genital division—which communicates with the 
pericardial division by three orifices in the septum—passes into the 
dorsal region and extends nearly as far forward as the middle of the 
ama ——— neph.p. 
bi. x VISCper 
Fic. 275. 
View of the ventral surface of a male Nautilus, the mantle-skirt being completely reflected 
so as to show the inner wall of the sub-pallial chamber and the four ctenidia and the foot cut 
short. a, muscular band, passing from the funnel to the integument; an, anus; c, mantle- 
skirt ; l.sp, aperture of the rudimentary left spermiduct ; neph.a, aperture of the left anterior 
kidney ; neph.p, aperture of the right posterior kidney ; olf, protective papilla of the osphra- 
dium; pe, penis; visc.per, left aperture of the viscero-pericardial sac; «, post-anal papilla. 
(After Lankester.) 
oesophagus (Fig. 270, 2). But the pericardial coelom is a flattened 
ventral cavity situated immediately beneath the body-wall: it contains 
the heart with its four auricles (Fig. 274) and the pericardial glands 
or portions of the follicular glandular appendages of the branchial 
vessels. In the Dibranchia, the coelom of the Decapoda contains 
the heart, the gonad, and the branchial hearts with their glandular 
appendages (pericardial glands, Fig. 273, ¢.b, x), but it is so much 
reduced in the Octopoda that it contains only the gonads and the 
appendages of the branchial hearts, its anterior part having dis- 
appeared (Fig. 278). 
In the Decapoda the coelom forms a vast pouch, with a 
constriction between the posterior or genital division and the 
anterior pericardial division, and it is produced into lateral annexes 
