the Worms of the Genutf Perichteta. 209 



and the two halves of which are rolled spirally round one 

 another. 



2. Two pyriform compact glands, situated in the sixth seg- 

 ment, formed of spherical cgeca arranged in a bunch, but 

 united by an interstitial substance. 



3. Two racemose glands, with spherical, isolated cseca, the 

 excretory canals of which, like those of the preceding glands, 

 open at the point of junction of the oesophagus and the parti- 

 tion 6-7. These last glands occupy the seventh segment. 



The gizzard, which is of a pearly -white colour, is remark- 

 able for the thickness of its muscular walls. The intestine 

 presents nothing peculiar. 



The nervous system is constructed on the ordinary plan. 

 The brain gives origin laterally to five pairs of nerves : one 

 branch springs from the commissure ; two pairs, the anterior 

 of which is the more slender, from each of the ganglia, in- 

 cluding that which closes the oesophageal collar. The anterior 

 ganglia, which are short and broad, become elongated in the 

 clitellum, and swell out again in the seventeenth, and espe- 

 cially in the eighteenth segment ; the ganglion of this latter 

 segment sends its anterior pair, which are very stout, to the 

 neighbourhood of the male genital orifices. 



The system of red vessels, constructed on the ordinary plan, 

 consists of a contractile dorsal vessel and of a ventral vessel. 

 From the ninth to the fourteenth segment, six lateral branches 

 of unequal size unite these two principal trunks : the first 

 are nearly cylindrical and narrow ; the last two, on the con- 

 trary, which are somewhat nodose (bosselees) and pyriform, 

 might be taken for cseca belonging to the ventral vessel ; they 

 are in reality united with the dorsal vessel by a small vascular 

 tube. The intermediate branches present a form intermediate 

 between these two extremes. Four of them appeared to us to 

 be very distinctly contractile, as, indeed, was indicated by the 

 interlaced muscular fibres which ran over their walls. 



Behind the cinctm'e the dorsal and ventral vessels are 

 united by a series of anastomoses, some adhering to the intes- 

 tine, others presenting a very curious arrangement. From 

 corresponding points in the dorsal and ventral vessels there 

 originate two slender vessels ; the first, after creeping over the 

 intestine, places itself side by side with the second, and 

 both, ramifying parallel, bury themselves in the walls of the 

 body, where their ultimate ramifications unite in the form of 

 loops. These loops occur upon the ovaries, the testes, and the 

 vibratile pavilions ; they are also seen in the cephalic region, 

 but there it was impossible to determine very distinctly the 



Ann. <i^ Mag. N. Hist. Ser. 4. Vol.\n\. 15 



