356 LECTURE XXIV. 



the funnel into the great anterior cava (^^. 137. a). In the Octopus 

 this vessel is provided with two semilunar valves at its commencement. 

 At its entrance into the pericardium it usually receives two large 

 visceral veins, and it divides into two branches {g, g), continued 

 downwards and outwards to the branchial hearts at the base of 

 each lateral gill : previously to communicating with these it dilates 

 into asinus, which also receives the venous blood from the sides of the 

 mantle. The two divisions of the vena cava, and also the visceral 

 veins (b, b), after having entered the pericardium, are furnished with 

 clusters of spongy or glandular follicles, which open into these veins by 

 conspicuous foramina. The follicles vary in form in different genera; 

 in the Eledotie they are elongated and pyriform : in the Argonauta and 

 Octopus they are shorter, and arranged in distinct clusters : in the Loligo 

 they are represented by a spongy thickening of the tunics of the veins : 

 in the Sepia the secerning appendages are more elongated, but are very 

 numerous, close-set, and of an irregular form, giving afloccular character 

 both to the great divisions of the vena cava and to those parts of the 

 visceral veins which are contained in the pericardial or great venous 

 cavity. The special compartments, into which these glandular ajj- 

 pendages to the veins are lodged, communicate with the respiratory 

 cavity by two papillary orifices, situated near the base of the gills. 

 As the kidneys derive their peculiar excretion from venous blood in 

 the lower vertebrated animal, Prof. Mayer's supposition * that the 

 venous follicles of the Cephalopods are analogous organs, is by no 

 means an improbable one. They may serve in a secondary degree 

 as temporary reservoirs of the venous blood when it is impeded in 

 its course thi'ough the gills ; and, as the venous follicles are endowed 

 with a peristaltic motion, they may regulate the quantity of blood 

 transmitted to the gills. 



The branchial circulation is, however, expressly provided with a 

 muscular ventricle (fig. 136. s) in the Dibranchiate Cephalopods, one 

 of these ventricles {fig- 137. h) being situated at the base of each 

 gill. The regurgitation of the blood into the glandular veins is pro- 

 vided against by the interposition of the two semilunar valves at the 

 entry of the ventricle. In the Decapoda and in the Argonaut, each 

 branchial ventricle has a fleshy appendage {k) attached to its lowest 

 surface. 



A single branchial vein which dilates into a small sinus (fig. 

 137. /) returns the blood to a single median systemic heart, which is 

 rounded in the Octopods, lozenge. shaped in the Calamaries, and fusi- 

 form, but bent upon itself, in the Sepia (fig. 137. m) Sepioteuthis, and 



* Analekten fur Vergleichenden Anatornie, 4to, 1835. 



