342 OBSERVATIONS ON THE CHLORAEMIDAE, 



branches on the stomach. In Siphonostoma diplocliciitos he des- 

 cribes the circulation as similar to that of Lophiocephalus, with 

 the exception that both dorsal and ventral vessels have a dilatation 

 situated much nearer the head. 



Qnatrefages* states that in Chloraema Dujardinii there are 

 two dorsal trunks, which are united in front and behind in all 

 the extent of the narrow part of the intestinal tube. But they 

 become isolated and attain a more considerable size on arriving at 

 the dilated portion possessing a layer of hepatic cells. Here each 

 of them becomes cemented to one of the sides of the digestive 

 tube, and they become united anew in the region of the oesophagus 

 to form a thick fusiform contractile trunk, which drives the blood 

 towards the branchiae. 



Claparedef describes the dorsal and ventral vessels inStylarioides 

 as both being simple, with lateral branches in each segment ; the 

 intestine is accompanied by two inferior enteric vessels situated 

 close together. G rube J merely mentions the presence of dorsal 

 and ventral vessels with transverse branches. 



In his "Recherches sur le systeme vasculaire des Annelides"§ 

 Jacquet describes at considerable length the vascular system in 

 Sijihonostoma diplocha'itos. He alludes to the observations of 

 Delle Chiaje, Costa, Quatref ages, and Claparede, already referred to, 

 with regard more especially to their interpretation of the character 

 of what he calls the dorsal vessel. Referring to the statement of 

 Claparede that the structure in question is a gland which has 

 been mistaken for a blood-vessel owing to its colour, he expresses 

 the opinion that this soi-disant gland only differs from the ordinary 

 blood-vessels in its deeper colour, which is due to its larger size 

 and the larger quantity of liquid which it contains as well as to 

 the presence of pigmented elements in its walls. 



* "Memoire sur la famille des Chloremiens," 'Ann. Sci. Nat.' 3e. serie, 

 t. xii. (1849). 



t " Annelides Ch^topodes du Golfe de Naples," p. 363. 

 X "Bemerkungen iiber die Familie der Chloraeminen," 'Bericht der Schles. 

 Gesellsch.,' 1876, p. 39. 



§ " Mittheil. a.d. zool. Stat, zu Neap.," vi. Bd. (1SS5), pp. 370-379. 



