296 
Abietinella to Abietinaria and Diphasia. They only differ from 
species of that genus in their hydrothecae being short-stalked, and, 
therefore, a concretion: between the stalk and the corresponding 
axis would convert them into Sertulareila-species. 
"There has not yet been found opereulate short-stalked species, 
corresponding to the other genera of the Sertulariidae, but that such 
forms have existed is evident from the fået, that a more or less 
developed stalk-mark is present in most species be- 
løonging to this family!) When a branch is regarded from 
one of the sides, this mark as a rule appears as a narrow chitinous 
process forming a continuation of the inner hydrothecal wall and 
running either downwards or obliquely inwards, but when we regard 
a hydrotheca from its inner, adcauline wall we see the whole stalk- 
mark (Pl. IV, figs. 25, 27) which is provided with a curved or 
sometimes angularly bent. proximal margin, and, therefore, its middle 
part is much shorter than the two lateral margins seen from the 
sides of the branch. Sometimes, however, we may also be able to 
see the whole stalk-mark, when a branch is regarded from the 
outer surface, f. inst. in Hydrallmania falcata. el. V, fg: 7.) 
In some species, f. inst. in Sertularia pumila, Odontotheca trispinosa 
and Abietinaria Coei' the stalk-mark when regarded from the 
side has the form of a short coecum-like projection, and in that 
case the stalk must have been provided with an adcauline con- 
cavity, which has prevented it from eoalescing with the branch 
in its whole length. In the two former species it is evident already 
from an outer inspeetion that this projeetion contains an inner 
cavity (Pl. IV, figs. 13,15, Pl, V, figs. 11, 14), the presence of 
which is confirmed by means of a sagittal section through a hy- 
1) While many BESS: have seen and figured the stalk-mark I have only 
found it mentioned by Clarke (15a) and Ritchie (51). Clarke 
who has seen it in Sertularia complexa describes it in the following 
way: .…: »chitinous processes extend downwards from the base of each 
hydrotheca, surrounding an aperture through which the body of the 
polypite is connected with the cænosare of the stem.« Ritchie 
who has seen it in Sertularia heterodonta and 8 rathbuni mentions 
it in the latter species as »two chitinous processes which project 
downwards and lie alongside the wall of the internode.« 
