61 
Pacific Species of "Lar” — Hand 
radial canal of each quadrant bifurcates rather 
symmetrically, whereas in P. circumsabella the 
primary canal seems to run directly to the 
margin, giving off its branches laterally. This 
difference is not absolute but applies in most 
specimens. 
A ring canal was present in most of the 
individuals observed, although the specimens 
possessing 32 or more tentacles did not show 
this structure. The disappearance of the ring 
canal seems to be a characteristic of adulthood 
of this genus. 
The bell of this species is somewhat thicker 
then that of the other two species, and, also, 
the tencency for the height to be the same as, 
or greater than, the diameter is striking. In 
preserved specimens the adoral end of the 
stomach never is located more than half the 
distance from the velar opening to the adoral 
tip of the bell (see Fig. 7). Fewkes (1889) 
described a slight constriction in the external 
outline of the bell at a level with the base of 
the stomach and showed this constriction in 
his figure. This constriction was apparent in 
two of the 31 specimens examined but ap- 
parently is not characteristic of the species. 
Fig. 7. Prohoscidactyla occidentalis. Whole medusa 
with tentacles shown on one half only. 
More commonly the bell is hemispherical or 
is of an elongate shape such as could be 
depicted by a figure representing slightly 
more than half of an oval. 
The nematocysts of the medusa present a 
familiar pattern. Only two kinds, macrobasic 
euryteles and desmonemes, are present, but 
a rather unusually shaped medium-size ma- 
crobasic eurytele occurs in the cnidothylacies. 
This nematocyst (Fig. 'bh) is distinctive of 
this species. In the tentacles a more usual, 
small, macrobasic eurytele is numerous, as 
are desmonemes. The nematocysts of this 
species were found to be as follows: 
Cnidothylacies 
Large macrobasic 
euryteles 24—28 X 1 1 — 14/1 
Medium macrobasic 
euryteles 12 — 17X 8— 12/t 
Desmonemes 5— 6X 4— 5/x 
Tentacles 
Small macrobasic 
euryteles 7— lOX 4— 5 m 
Desmonemes 5— 6X 4— 5 m 
Figure 3^-/ illustrates the nematocysts of this 
species. 
THE hydroid: The hydroid stage of this 
species resembles in its general form that of 
other known species, its most singular char- 
acter being that the gonophores bear large 
numbers of medusa buds which were not 
discerned to have a regular arrangement upon 
the gonophores. A maximum of 12 buds was 
found to occur on a single gonophore among 
the colonies examined. This material was col- 
lected on April 12, 1952. 
The gastrozooids are arranged around the 
lips of sabellid tubes, sometimes forming a 
complete circle, the two tentacles and mouth 
facing the orifice of the tube. One colony, 
which was growing on a tube which was 
damaged on one edge, was located about 1.5 
millimeters inside the lip of the tube. Because 
of the manner in which the lip of the damaged 
tube flared out, this placed the colony in 
