SEA-FISHERIES LABORATORY. 227 



suggests that it is possibly derived from the yellow 

 lipochrome. Fauvel (O.R. Acad. Sciences, Paris, Tome 

 129, p. 1273) has recently adduced evidence in support of 

 this suggestion, showing that the formation of melanin 

 granules may be due to a chemical modification of the 

 lipochrome taking place in the interior of the cells under 

 the influence of some acid. 



General Anatomy of the Internal Organs. 

 (See Plate III.) 



The body cavity is best opened by an incision through 

 the body wall along the mid-dorsal line. It often 

 happens that in freshly killed specimens the middle part 

 of the alimentary canal is forced out through the incision 

 owing to the fact that the animal has died somewhat 

 contracted, and the contents of the ccelom are under con- 

 siderable pressure. At the same time a quantitjr of the 

 coelomic fluid will escape through the aperture. 



The coelom is spacious and continuous from one end 

 of the animal to the other. In front it is sub-divided 

 transversely by three fenestrate!/ septa, or diaphragms. 

 The first of these is placed at the anterior boundary of the 

 first chsetigerous segment, and is inserted into the body 

 wall at the level of the anterior edge of the first chaetigeroUs 

 annulus. It is perforated by some of the retractor 

 muscles of the pharynx by which, in some specimens, the 

 septum is pulled back ventrally, so that at first sight its 

 ventral edge appears to be inserted near the posterior 

 margin of the first chaetigerous annulus. Further 

 examination shows that the diaphragm is not obliquely 

 placed, but is situated dorso-ventrally at the anterior edge 

 of the annulus. The second and third diaphragms mark 

 the posterior limit of the second and third chaetigerous 



