60 



ALLAN HANCOCK PACIFIC EXPEDITIONS 



VOL. 15 



Proboscidial oi*c(ans 



Neural 

 gang'lion 



Connective 

 tissue 



=?=»- Circular 

 muscles 



Inner 

 space 



Coelomic 

 space 



Peritoneum 



Epithelium with 

 cuticular surface 



Longitudinal 



muscles 



TEXTFIGURE 3 



Glycera oxycephala Ehlers, cross section of the proboscis at the distal 

 third, showing the relation of the proboscidial organs to under- 

 lying structures, x 70. 



The proboscidial organs of the external cylinder are in intimate 

 contact with the surface and are penetrated by vacuolated tissues; the 

 presence of muscular tissue within them seems likely but has not been 

 proven. Each organ contains a few large cells, visible even in 

 unstained tissue, in addition to many much smaller cells. The large 

 cells are of 2 kinds; there are one or 2 larger basal cells and about as 

 many smaller axial cells (see Oppenheimer, 1902, p. 558, for termin- 

 ology). The basal cells are large, circular or oval and located at or 

 near the base of the proboscidial organ. The axial cells are smaller and 

 spindle-shaped ; they lie along the length of the organ and have neural 

 connection with the nerve ganglion and plexus in the connective tissue, 

 as also with a circlet of nerves at the distal end or about the aperture 

 of the proboscidial organ. It is likely that these axial cells aid in the 

 control of the aperture at the distal pore. The function of the larger 

 cells is not clear, but they may be expected to be secretory. The sim- 

 ilarity of these organs in members of the GLYCEREA is striking, 

 but there is much diversity of their external parts. 



