5l4 MAYNARD M. METCALP, 



extends into the raphe where it becomes intimately associated with 

 the great rapheal muscle (cf. Text-Fig. E). The nerve extends three- 

 fourths of the way to the ventral end of the raphe, gradually dimin- 

 ishing in size until it disappears. 



Boltenia is the easiest form I have yet found in which to de- 

 monstrate by dissection the disposition of the great rapheal muscle. 

 It is attached below to the upper edge of the oesophageal opening. 

 Above, it connects with the muscles above the ganglion, its fibres 

 being distributed to the siphons, becoming the doral strands of the 

 siphon retractors. 



The point of chief interest, which is demonstrated with great 

 clearness in Boltenia, is the innervation of the ciliated funnel. A 

 large, very richly gangliated nerve pushes out from the right side of 

 the ganglion, near its anterior end, and is distributed to the columnar 

 epithelium of the duct of the neural gland, just above the point where 

 the latter passes over into the ciliated epithelium of the funnel (n 

 Fig. 19 and Text-Fig. F). Fig. 21 shows that at this point the 

 basement membrane of the duct is absent, and the outer ends of the 

 cells are drawn out into long processes. I have not had living 

 material for study, so I have been unable to demonstrate by either 

 methyl blue or gold chloride, or by maceration, the shape of the in- 

 dividual cells, or their actual continuation into the fibres of the nerve. 

 There is, however, no room for doubt that this large nerve, which 

 runs to the epithelium at this point, and whose fibres cannot be 

 traced farther, really innervates the epithelium of the duct where it 

 joins the ciliated funnel ^). Figs. 22 and 23 show three of the ganglion 

 cells from this nerve. They have the same character as the larger 

 cells in the cortex of the brain itself. I shall call attention later 

 (p. 552) to this innervation of the funnel in Boltenia as one of the 

 several things indicating that the ciliated funnel of the Tunicata 

 has a sensory function. 



Boltenia in comparison with the Cynthias shows the same general 

 relations except for 1) the symmetrical arrangement of the rapheal 

 nerve, which arises from the posterior mid-point of the ganglion, 

 2) the absence of any sign of a rapheal duct and 3) the great clearness 

 with which the innervation of the ciliated funnel can be demonstrated. 



1) In material preserved in formalin and stained with Mayeb's 

 haemalum or Delafield's haematoxylin, the nerve cells and nerve fibres 

 are almost black, giving a sharp contrast to the blood corpuscles and 

 connective tissue. 



