Lectures on the comparative anatomy and physiology of the invertebrate animals : delivered at the Royal College of Surgeons . he Cephalopods possess the power of emitting a luminoussecretion. | All of them are nocturnal and social animals, and arereadily attracted by bright metallic substances. Prior to the dissection of the Pearly Nautilus, the Cephalopodswere regarded as having three distinct hearts; but two of these, whichare appropriated to the branchial circulation, are peculiar to the higherorder, and are perhapsthe main-spring of theirsuperior muscular ener-gies. In the Dibranchiatesthe
Lectures on the comparative anatomy and physiology of the invertebrate animals : delivered at the Royal College of Surgeons . he Cephalopods possess the power of emitting a luminoussecretion. | All of them are nocturnal and social animals, and arereadily attracted by bright metallic substances. Prior to the dissection of the Pearly Nautilus, the Cephalopodswere regarded as having three distinct hearts; but two of these, whichare appropriated to the branchial circulation, are peculiar to the higherorder, and are perhapsthe main-spring of theirsuperior muscular ener-gies. In the Dibranchiatesthe venous blood returnsfrom each arm along itslateral and posterior partsby two veins, whichseverally unite at thebase of the arm with theopposite vein of the ad-joining arm, the wholebeing ultimately con-veyed to an irregularcircular sinus, which sur-rounds the pharynx, andis continued between theanterior cava {fig. 228, a).two semilunar valves at its commencement; in Sepia witli a singlevalve. At its entrance into the pericardium it usually receives twolari^e visceral veins, returning the blood from some large irregular. Sepia officinalis. head and the funnel into the greatIn Octopus this vessel is provided with * XXIV. p. 329. f Linnffius quotes a passage from Bartholinus, illustrative of the luminoussurface of a species of Octopus which shone so hrightly, ut totum palatiumardere videretur. This phosphorescence might be post-mortem, and the result ofcommencing decomposition. CEPHALOPODA. 625 abdominal sinuses, and it divides into two branches {g, g), con-tinued downwards and outwards to the branchial hearts at the baseof each lateral gill: previously to communicating with these itdilates into a sinus, which receives the venous blood from thesides of the mantle. The two divisions of the vena cava, and alsothe visceral veins (b, b), after having entered the pericardium,are furnished with clusters of glandular follicles, which openinto these veins by conspicuous foramina. The fol
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