24 University of California Publications. | ZOOLOGY 
According to Nutting (:04, p. 42), ‘‘it occurs not infrequently 
in several widely different forms among the Sertularidae that a 
gonangium will occasionally have its origin within the lumen 
of the hydrotheca, although these species normally produce gon- 
angia in the ordinary position.’’ The very fact that what is 
typical of S. halecina is atypical of most other sertularians, 
though not infrequent, and what is occasional in S. halecina is 
usually typical of the others, only leads to a rejection of the 
view which lays more than specific importance on the difference 
in the typical position of gonangia in different species. 
Fig. 14.—Sertularella Fig. 15.—S. halecina. Fig. 16.—S. halecina. 
halecina. Portion of Portion of stem show- Portion of colony. Show- 
stolon with gonan- ing origin of branch ing an extrathecal branch 
gium (s); base of one just below hydrotheca (x). 
stem, with intrathecal (x). 
gonangium (i). 
If the branches of S. halecina be now considered, it will be 
seen that they, as well as the gonangia, emerge typically from 
hydrothecae. In this respect, then, S. halecina is a Thecocla- 
dium. Yet this character is not invariable. Occasionally 
branches arise independently of hydrothecae. Four such cases 
are shown in figs. 15, 16,17, 18. In figs. 15, 17, 18, the branches 
arise on the bulging stem just beneath hydrothecae, a familiar 
origin of branches in the Sertulariidae. In fig. 16, the branch 
is not associated with a hydrotheea in any way. All these cases 
(except fig. 17) were found on the same colony; and it is inter- 
