BY WILLIAM A. HASWELL. 347 



dark body, which is continuous behind with the wall of the 

 stomach. This peculiar dark body is composed of different 

 strands irregularly entwined and mostly with an oval transverse 

 section, formed of cells filled with brown granules, the cell-struc- 

 ture not being always distinctly visible. He does not definitely 

 suggest any function for the dark glandular body, but points out 

 that it has its homologues in various sedentary Annelids — such as 

 Terebella and Cirratulus — as well as in Polyophthcdmus, Cteno- 

 drilus, and Enchytraeus. 



Cunningham* states that in Trophonia plumosa the somewhat 

 cylindrical cords, of which the cardiac body is made up, are seen 

 in sections not to be composed entirely of cells, but in most cases 

 to possess a lumen, the cells around which form a glandular- 

 looking epithelium of several layers — the more internal clear and 

 vacuolated. He finds no trace of any opening either in front or 

 behind. In Flabelligera affinis ( Siphonostoma) the organ in 

 question is very different ; it is relatively narrow and occupies 

 only a small part of the lumen of the heart ; it has the form of a 

 narrow irregular flat band, which in transverse section appears as 

 an irregularly branching narrow tract without distinct lumen, 

 the walls being in close contact. The clear vacuolated cells are 

 absent — the epithelium consisting entirely of elongated columnar 

 nucleated cells ; and the granules are smaller and less numerous. 

 Cunningham dissents from Horst's view that the organ in 

 Enchytraeus is homologous with the cardiac body of the Chlorae- 

 midae. He states that in Tropihonia there is no connection 

 between the cardiac body and the intestinal epithelium. 



In Goppingeria, Stylarioides cinctus, and S. Horstii, and Sip>honos- 

 tomum affine, this cardiac body is a greatly-elongated dark-coloured 

 structure, which lies in the interior of the heart or contractile 

 dorsal vessel. In front it is very narrow (fig. 20 c. b.) and does not 

 nearly fill up the lumen of the vessel ; but further back it is 

 broader, and in sections appears completely to block up the cavity. 



* "Some points in the Anatomy of the Polychseta," 'Quart. Journ. Micro. 

 Sci.' vol. xxviii. 



