254 DESCRIPTIONS OF RARTHWORMS. 



I suppose that some of the muscular bands , radiating from 

 the intestine to the body- wall, increased in size and thus 

 grew similar to real septa. The first three pairs of trans- 

 verse hearts arise simply from the dorsal trunk , but the 

 two posterior pairs of them communicate also with the 

 supra-intestinal vessel (v. typhlosolien) ; from the last vessel , 

 in the region between the 2nd and 3rd pair of hearts, 

 arises also a pair of lateral vessels (fig. 1 , Iv) which pass 

 beneath the second transverse heart and , running forward 

 along the side of the gizzard till the cephalic part of the 

 body, supply the body-wall with several branches. In the 

 9th segment the lateral vessels of both sides communicate 

 with each other by a transverse vessel , that passes beneath 

 the middle of the gizzard. 



In Ac. ungulatus the vascular system shows a curious 

 difference in its arrangement from that of Ac. Schlegelii\ for 

 in that species the lateral vessels do not only arise from the 

 underside of the intestine , where they unite in a single 

 sub-intestinal vessel^), but in the 5th segment, on the 

 limit of the pharynx and of the oesophagus , they com- 

 municate with each other by a transverse vessel, which 

 passes above the intestine. 



In Ac. Schlegelii I found two pairs of spermathecae in 

 the 8th and 9th segment; they are oval pouches, without 

 any diverticulum , opening unto the exterior by a short 

 efferent duct, in the series of the internal bristle of the 

 dorsal pair. Spermathozoa have not been observed therein. 



In Ac. ungulatus the efferent duct of the spermatheca 

 is furnished at its upper extremity with a slight protube- 

 rance , though , as rightly stated by Beddard , it is hardly 

 so marked a diverticulum as figured by Perrier. This 

 protuberance appears to be the seat of a strong secretion; 



1) A curious mistake has crept in Beddard's figure of the vascular system 

 of Ac. Layardi (loc. cit.); for according to this drawing the lateral vessels 

 seem to arise from the dorsal side of the intestine, while in the text of his 

 paper he says exactly: «these vessels pass heneath the intestine and unite 

 to form a single subintestinal vessel." 



Notes from the Leyden IMuseuxn, "Vol- UC. 



