RINGED- WOKMS. 211 



dividing it, as it were, into cells. Two conical yellow coecal pouches 

 are placed at the commencement of this portion of intestine : they 

 may probably be considered to be rudiments of the liver. In 

 the common Leech, the short oesophagus, of an oval form, wider 

 towards the middle of its length, passes into a long stomach, which 

 is divided by transverse walls into eleven portions: on each side are 

 seen ten coecal appendages to the stomach, the last of these being 

 the longest ; the inferior opening of the stomach (Pylorus) extends, 

 like a funnel, into the intestine by a narrow opening. In other 

 genera of Hirudinea, ex. gr. in Hcemopsis, the intestinal canal is 

 more simple, having only two ccecal appendages 1 . In Aphrodita 

 there succeeds to a very muscular cylindrical tube, which PALLAS 

 described as stomach, a thin intestinal canal of considerable width 

 with about twenty coecal appendages on each side 2 . These append- 

 ages are narrow at their insertion into the intestine, wider in their 

 middle, where they are provided with branched lappets, and termi- 

 nate in longish ccecal sacs. This structure recalls the disposition 

 of the intestinal canal in Planarice and Distomata, and the blind 

 branched appendages of the intestinal canal in Star-fishes may be 

 compared with it. They are filled, as these are, with yellow fluid, 

 and may be compared to rudiments of liver. In other animals again 

 the liver appears as a protrusion of the intestinal canal. 



The system of Blood-vessels presents very many modifications 

 in this class. As to the blood itself, we have seen above, that 

 CUVIER believed it to be red in all the ringed-worms. Such is 

 really the case in by far the greater number, as Hirudo, Lumbricus, 

 Arenicola, Nereis, Terebella, Serpula, &c.: in others it is nearly 

 colourless, as in Aphrodite: yellow, as in Polynoe and Phyllodoce, or 

 even green, as MILNE EDWARDS found it in a species of Sabella. The 

 general arrangement of the circulating apparatus is as follows: there 

 are two main stems, one on the dorsal surface, the other on the 

 ventral surface, which run in the midst through the whole length 

 of the body, and as far as the course of the blood could be deter- 

 mined in the living body (for which investigation small indivi- 

 duals are frequently more fitted than large ones, on account of their 



1 See a figure in BRANDT und RATZEBURG, Medizinische Zooloyic, n. Bd. 1833, 

 Tab. xxix. B. fig. 12. 



2 PALLAS, 1. 1. Tab. vn. fig. lod, d, fig. ng,g. G. R. TREVIRANUS in Zeiischrift 

 fur Physiologic in. 1829, s. 159 161, Tab. xn. fig. 9. 



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