60 
Proboscidactyla occidentalis (Fewkes) 
In 1889, Fewkes described a medusa, Willia 
occidentalism from near Santa Cruz Island. From 
his description it is clear that this medusa is 
a Proboscidactyla m and, moreover, it is presumed 
that this species is identical to that found at 
La Jolla, California, because a single specimen 
collected in 1950 near Santa Cruz Island is 
identical to the more abundant La Jolla mate- 
rial. Thirty-one medusae with 8-40 tentacles 
have been examined from the San Diego area, 
as well as a single 28-tentacle specimen from 
Santa Cruz Island plus 18 colonies of a hy- 
droid which have been assigned to this spe- 
cies. The hy droids were found on sabellid 
tubes which were associated with a kelp hold- 
fast. This kelp holdfast was growing in 40 to 
50 feet of water and was obtained by Conrad 
Limbaugh on April 12, 1952, while diving 
with an aqua-lung at La Jolla. The samples 
from which the medusae were obtained were 
collected by Conrad Limbaugh, Robert Bieri, 
and John Bradshaw, of the Scripps Institution 
of Oceanography. 
THE MEDUSA: Medusae of this species have 
been found in plankton samples collected at 
Santa Cruz Island in the month of March, 
1949, and from La Jolla and San Diego Bay 
during the months of March through July, 
1952. The largest medusa collected was a 
female 3.5 millimeters high by 3.5 millimeters 
in diameter. This medusa possessed 40 well- 
developed tentacles. The smallest medusa was 
slightly greater than 1 millimeter in height 
and diameter and possessed eight tentacles. 
In life little pigment is to be seen on these 
medusae, except for the dark reddish-brown 
to black bulbs of the tentacles. Some speci- 
mens show a little light-brown pigment in 
the stomach walls. 
The gonads are apparent on 8-tentacled 
medusae but do not begin to bulge from the 
adradial walls of the stomach until about the 
16-tentacle stage. The gonads appear ripe at 
the 32-tentacle stage, and the female possess- 
ing 40 tentacles seemed to have shed part of 
PACIFIC SCIENCE, Vol. VIII, January, 1954 
the eggs from one quadrant of the gonads. 
As in the other species of Proboscidactyla ^ the 
gonads do not fuse across the radial margins 
of the stomach and are disposed as four in- 
terradial masses consisting of paired adradial 
lobes connected at the interradii by thin 
sheets of gonadial tissue. The gonads, when 
fully ripe, show folds along their medial 
surfaces. The sexes are separate. 
The manubrium is very short and the lips 
are highly folded. This species closely resem- 
bles P. flavicirrata in this respect. 
The radial canals branch, and the general 
pattern and order of development is presented 
in Figure \a-c. Small variations in the location 
and length of the branched canals occur from 
quadrant to quadrant and specimen to spec- 
imen; however, the order and final arrange- 
ment seems to be relatively definite so that 
when the 32 -tentacle stage has been reached 
a difference in pattern of branching is ap- 
parent when it is compared with the same 
stage of P. circumsabella. This difference con- 
sists of a pair of fourth order tentacles span- 
ning the second order tentacle in P. occidentalism 
whereas in P. circumsabella a pair of fourth 
order tentacles span the left hand third order 
tentacles (compare Fig. \c and l/). 
In the figure of this species in Fewkes 
(1889) a 20-tentacle medusa is shown. This 
is presumably a fleeting stage in development 
in which the first of the fourth order tentacles 
had appeared. The radial canals shown in 
Fewke’s figure represent a condition seldom 
attained in this species in that he has shown 
the canal branched into three equal parts, 
with each of the lateral branches possessing 
another branch. The manner in which the 
canals of all species of Proboscidactyla branch 
is such that this is nearly an impossibility. It 
is presumed that Fewkes drew a symmetrical 
diagram which was not a copy of the actual 
pattern present. It will be noticed, if one 
compares the figures of the three species of 
this report showing the systems of branching 
canals, that P. occidentalis and P. flavicirrata 
tend to present a pattern in which the primary 
