02 



fold here semis off rather larger vessels, thai form a some- 

 what coarser meshwork in the seventh element, and so 

 on, till the secondary elements are reached. Now, in 

 the axis of each gull filament, about halfway between 

 the internal and external surfaces, runs the artery from 

 this leaflet, out to the efferent gill vessel (fig. 61, A x ). 

 It originates in branches from the network of vessels in 

 the secondary elements of the gill, and (he latter musl 

 he turned aside to disclose both (lie artery and the 

 network (fig. (il, N. ). 



The efferent vessels of the accessory leaflets also 

 originate in a network of capillaries. The meshwork 

 of arteries increases in size in succeeding elements of the 

 gill. Ultimately they open into two vessels: (a) A 

 sinuous vessel common to, and between the two leaflets, 

 and opening into the efferent vessel of the true leaflet 

 between them, but on the opposite side of the gill (fig. G3, 

 and (b) A sinuous vessel on the other side of each 

 accessory leaflet, running into the efferent vessel of the 

 leaflet adjacent (fig. 63, 2). 



The so-called Spleen or branchial gland of bhe 

 Cephalopods, would appear to have some intimate con- 

 nection with the blood,' as it is irrigated by both arterial 

 and venous blood, and is placed close to the gill. It is 

 built up of polygonal cells, separated by lacunae of 

 various sizes containing blood (PL VI, fig. i)'A<i ; b.s. and 

 l.b.s.). There are no true capillary vessels whatsoever. 

 It receives blood: (1) from branches which, coming 

 from the- afferent vessel, furnish venous blood (fig. 

 63, Aff.v); and (2) from arteries running down 

 the supporting pillars of the branchial leaflets. These 

 arteries originate in a network formed by the arteries 

 of the accessory gills (fig. 63). This blood mixes 

 in the intercellular lacunae of the branchial "'land, 



