206 CIRCULATION IN CEPHALOPODA. 



receiving blood from various little tributaries, again divides 

 into two branches (e e). Each branch is here joined by a 

 vein (o) of a size equal to itself, and which has brought the 

 blood from the abdominal viscera ; and a little afterwards 

 by another, from the cloak and the supports of the gills. 

 When thus augmented they proceed to their termination in 

 the lateral hearts, placed, one on each side, at the root of 

 the branchiae. These hearts (/) are called pulmonic ; * they 

 are rather cellular than fleshy in texture, moderately thick, 

 of a blackish grey colour in some genera, pale red in others, 

 and pitted internally with many little cavities communi- 

 cating together. Two large valves are placed at the venous 

 orifice to prevent regurgitation ; but there is none at the 

 orifice by which the blood enters the artery (g\ whose 

 function is to carry it forwards to the gills or branchiae (h\ 

 where, circulating through the windings of their beautiful 

 leaflets, it is purified, and thence returned by veins running 

 in the reverse direction, and which open at last by a single 

 trunk (i) into the systemic heart, again to run the same 

 endless circuit, f 



I have omitted in this description a very remarkable 

 peculiarity connected with the venous system, and which 

 merits our particular notice. Previously to their junction 

 with the pulmonic hearts, the two branches into which the 

 great dorsal vein bifurcates, and their accessory veins, pass 

 across two large cavities, called venous by Cuvier, which 

 communicate externally by an aperture on each side near 

 the gills. In this part of their course the veins are gar- 

 nished with some very singular glandular bodies (x x, Figs. 

 38, 39) of a spongy cellular structure, and yellow colour, 

 from which an opaque yellowish mucous secretion can be 

 easily pressed in considerable quantity. The cells of these 

 bodies open freely into one another, and they have likewise 

 a very free and direct communication with the interior of 

 the veins to which they are appended (Fig. 39), but of 

 their use it is difficult to form an opinion. Cuvier makes 

 several suppositions : they may be, he says, diver ticula, 

 in which the venous blood is more fully exposed to the 

 purifying influence of the circumfluent water ; or they may 

 be excretory canals, by which the spongy glands pour 

 into the vein some substance which it could not of itself 



* Lister mistook them for ovaries. Exer. Anat. tert. xxxiv. 



f " The form of the systemic ventricle varies remarkably in the naked 

 Cephalopoda, as well as the direction in which it is extended ; but there is 

 great uniformity in the distribution of its vessels." GRANT in Zool. Tram. 

 i. 83. 



