CEPHALOPODA. 625 



abdominal sinuses, and it divides into two branches {g, g), con- 

 tinued downwards and outwards to the branchial hearts at the base 

 of each lateral gill : previously to communicating with these it 

 dilates into a sinus, which receives the venous blood from the 

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

 the visceral veins (i, h), after having entered the pericardium, 

 are furnished with clusters of glandular follicles, which open 

 into these veins by conspicuous foramina. The follicles vary 

 in form in different genera; in Eledone they are elongated and 

 pyriform : in Argonauta and Octopus they are shorter, and arranged 

 in distinct clusters : in Loligo they are represented by a spongy 

 thickening of the tunics of the veins : in Sepia the secerning ap- 

 pendages are more elongated, but are very numerous, close-set, and 

 of an irregular form, giving a floccular 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 appendages to the 

 veins are lodged, communicate with the respiratory cavity by two 

 papillary orifices, situated near the base of the gills. Cuvier had 

 suggested that these appendages might serve to eliminate some prin- 

 ciple from the blood : and, as the kidneys derive their peculiar excre- 

 tion from venous blood in the lower Vertebrata, Mayer's supposition* 

 that the venous follicles of the Cephalopods were analogous organs, 

 was not an improbable one : it has since been confirmed by the dis- 

 covery in them of purpurate of ammonia, f They may serve in a 

 secondary degree as temporary reservoirs of the venous blood when 

 it is impeded in its course through the gills ; and, as the venous fol- 

 licles are endowed with a peristaltic motion, they may regulate the 

 quantity of blood transmitted to the gills. 



The accessory hearts {Jig. 228, h, h) are situated one at the base 

 of each gill. The regurgitation of the blood into the glandular veins 

 is provided against by the interposition of the two semilunar valves 

 at the entry of the ventricle, where it receives the blood from the 

 great vein. In the Decapods and in the Argonaut, each branchial 

 ventricle has a fleshy appendage {x) attached to its lowest surface. 

 Cuvier correctly observes that the ventricle itself is more cellular 

 than fleshy % : but its direct connection with the branchial inferent 

 vessel, and its valvular structure, incline me to regard it as more 

 properly belonging to the circulatory than the aquiferous system. 



A single branchial vein which dilates into a smaU sinus (^Jig. 228, T) 



* Analekten fur Vergleichenden Anatomie, 4to. 1835. 



t XXIV. p. 400, X CCCXXI. p. 2a pL ii. fig. 3, 12. 



s s 



