SANGUIFEROUS SYSTEM. 433 



abdominal bands as far as the cloaca, they give off numerous 

 branches to the superficial parts, and to the tubular ciliated 

 feet, which are here projected from the sides, as in other 

 genera. Other important branches arise from this wide, 

 arterial, oesophageal ring, which pass forwards and backwards 

 to the more deeply seated viscera. The venous intestinal 

 trunks follow the windings of the long alimentary canal, and 

 their branches anastomose most freely with each other on 

 the mesentery of these animals, as in the vertebrated classes. 

 Distinct pulsation is observed in the great arterial trunk and 

 circle around the oesophagus, which gives origin, as usual in 

 this class, to the principal arteries of the body. The blood 

 accumulated in the larger vessels manifests a reddish hue 

 during life, and abounds with globules which unite in a coa- 

 gulum after death. There appears likewise to be a vascular 

 ring around both extremities of the body in the elongated 

 trunk of the sipunculus, and the large connecting median 

 artery, like the dorsal artery of articulata, gives off numerous 

 lateral branches in its course forwards. This artery forms a 

 small sinus at both ends, and gives off the tentacular and other 

 cephalic branches from the cesophageal ring, which it here 

 forms, as in other echinoderma. Regular pulsations have 

 been observed in this long narrow vessel, as in the principal 

 trunk of holothuria, and in its terminal enlargements, and 

 the blood has a pale red colour, as in the large arterial trunks 

 of many species of asterias and other genera of this class. 

 The same vascular ring, sometimes double or triple, around 

 the oesophagus, formed by the union of the mesenteric and 

 the general systemic veins, observed in most of the larger 

 asterida, echinida and holothurida, is seen even in the smaller 

 forms of ophiurte, where it also radiates arterial trunks to 

 the superficial and the deeply seated parts, and to the vesi- 

 cles and ampullse of the feet. The pale red colour so gene- 

 rally perceptible in the blood of the echinoderma, was ob- 

 served by Cavolini even in that of zoophytes, especially in 

 the longitudinal vessels which occupy the superficial grooves 

 of the axis of gorgonia, corallium, and other corticiferous 

 forms ; and Chiaje observed a yellowish hue in the thin se- 

 rous fluid, abounding with blood-globules, so extensively 

 circulated through the superficial and the deep seated vessels 

 even of the minutest forms of acalcpha. There is thus in 



PART V. F F 



