ZooL— Vol. II.] ROBERTSON— ENTOPROCTA. 33 1 



ovaries contained ripe products, and the brood-sacs were 

 filled with embryos in every stage of development, 



(h). The Stalk. — Externally, the stalk shows the two 

 regions, dorsal and ventral, already described for the calyx. 

 The dorsal side is characterized by the presence of spines 

 which, however, have no regular arrangement. The ven- 

 tral side occupies about one-fourth of the circumference 

 (figs. II, 12, V. 5.). The cuticle of this portion is thin and 

 is thrown into many transverse wrinkles by the contraction 

 of the muscles beneath (fig. i, sfl. reg.). 



The Musculature. — The stalk is of the type holosarcine. 

 The muscle forms a cylindrical sheath just beneath the 

 ectoderm. The sheath, as a whole, is much thicker than 

 in other Pedicellines, and its thickness is considerably 

 greater on the ventral side than on the dorsal (figs. 11, 12, 

 V. m. sth.). In the ventral region the fibers are longitud- 

 inal (fig. 2, V. ni.). From a line in the middle of the dorsal 

 region the fibers take an oblique direction on both sides 

 toward the ventral side (fig. 2, o. m.f.). 



In the lower part of the stalk and in the stolon just below 

 the stalk, large granular cells, with very large nuclei, attract 

 the attention, even in an unstained specimen. Frequently 

 there are several processes to each cell. They are often 

 found part way up the stem united together by these pro- 

 cesses, resembling a string of beads. These are probably 

 the myoblasts, from which the muscle fibers originate. The 

 muscle fibers which are not continuous with those of the 

 calyx are attached at their distal end to the septum between 

 calyx and stalk. Proximally, both longitudinal and oblique 

 fibers pass into the stolon, spread out in radiating directions, 

 and become attached to its base. Besides the myoblasts 

 already mentioned, the interior of the stalk is filled with 

 mesenchymatous tissue, resembling that filling the space 

 between the body-wall and the alimentary canal of the calyx. 



(c). The Neck. — The extensive development of the ven- 

 tral muscles and the continuity of many of the muscle fibers 

 from stalk to calyx have produced an appearance at the 

 junction of head and stem very unlike that commonly seen 



