332 CALIFORNIA ACADEMY OF SCIENCES. [Proc. 3D Ser. 



in the Entoprocts. Generally, the neck is small and the 

 infolding of the cuticle to form the septum is alike on all 

 sides. The plug of cells usually occupies a central position, 

 and the regenerative cells are of equal size and are symmet- 

 rically arranged. A very different condition prevails in 

 Myosotna. The neck is stout and broad. On the ventral 

 side the stalk extends part way up the calyx, as shown in 

 polypides three and four of fig. i. The plug of cells is 

 nearer the dorsal than the ventral side, and the regenerative 

 zone is not symmetrically disposed. Figure 3 represents 

 these conditions in part. This section does not show the 

 calyx in its natural or usual position. It is thrown backward 

 too much and makes the plane of the lophophore almost 

 horizontal. The evidence that this is an unnatural position 

 is found in the distortion of the cells (fig. 3, cl. els.) which 

 bridge over the opening in the center of the septum. In 

 the normal condition these cells should be horizontal. This 

 very distortion gives the best view of the ventral muscle 

 and it was for this reason that the section was chosen. If 

 proper allowance be made, the thickness of the neck, the 

 proximity of the plug of cells to the dorsal side, and the 

 asymmetry of the regenerative zone are plainly manifest in 

 fig. 3. Figure 13 represents the usual appearance of the 

 neck in the Pedicellines. Comparison of this with fig. i 

 will perhaps make the difference more obvious, although 

 allowance must be made for a difference in magnification. 



-B. Regeneration. 



Corresponding to this thickness of the neck, there is a 

 firmness of attachment between stalk and calyx very differ- 

 ent from the fragile connection usually presented by this 

 family. In Myosoma the calyces do not drop off easily, at 

 least in preserved specimens. Experimentation seems to 

 show that there is a greater tendency to break away from 

 the stolon than for calyx and stem to separate, especially in 

 the case of the younger polypides. In attempting to sepa- 

 rate polypide and stolon by pulling them apart, the stem, 

 in each case, stretched considerably before any break 



