56 
PACIFIC SCIENCE, Vol. VIII, January, 1954 
H MM 
Fig. 4. The hydroid of Prohoscidactyla flavkirrata. 
a. Young gastrozooid with a "tail”; b, a colony, only 
part of which is shown, as seen by looking down upon 
the end of a worm tube; c, gastrozooid and gonozooid, 
the latter with several medusa buds. 
networks to very random, irregular networks. 
It was noted that the nine colonies showing 
the less parallel hydrorhizal networks also 
possessed very slightly smaller gastrozooids 
than the other seven colonies and that these 
nine colonies were the only ones possessing 
scattered gonozooids or no gonozooids at all. 
Some of these colonies were obviously im- 
mature, whereas others were quite mature. It 
was thought that these nine colonies might 
be of some other species, but this idea was 
discarded as no differences between these and 
the larger colonies could be found in their 
nematocysts. So far no one has demonstrated 
whether a single colony of ”Lar” produces 
only one sex of medusa or whether both sexes 
can be produced by a single colony, so the 
suggestion may be tentatively put forth that 
the visible morphological differences in the 
Puget Sound "Ear” may be of a sexual nature. 
The color of this hydroid in life is, in gen- 
eral, orange to pink with the color restricted 
to the endoderm as in other species. The 
gastrozooids are 0.8-1. 2 millimeters tall by 
about 0.2 millimeter in diameter. The gono- 
zooids are in general thinner and slightly 
shorter than the gastrozooids. Two tentacles 
are present on the gastrozooid and none on 
the gonozooid. The size of the Puget Sound 
individuals is slightly larger than that of those 
from Japan, and no variation in tentacle num- 
ber was noted, whereas a number of speci- 
mens with extra tentacles was reported from 
Japan. The Puget Sound "Ear” possessed 
from two to eight medusa buds, commonly 
eight, with four of the buds large and well 
developed and four as small, poorly developed 
medusae. The four small buds alternate with 
the four large ones, and all buds seem to arise 
at a single level slightly above the middle of 
the gonozooid. 
The nematocysts of the hydroid are as 
follows : 
Macrobasic euryteles. ....17— 25X8— -12/i’ 
Earge microbasic euryteles 10—18X4 — (y\x 
Small microbasic euryteles 5— 6X2— 3/x 
Desmonemes. 3— 5X2— 4/x 
The tentacles of the polyps seem to possess 
only the small microbasic euryteles listed 
above, whereas the three remaining types were 
found in the caps of the polyps. The des- 
moneme and the large microbasic eurytele 
also occur in small numbers over the surfaces 
of the polyps. Figure "ya-d illustrates the ap- 
pearance of the nematocysts of this hydroid. 
THE HOSTS: Uchida and Okuda (1941) re- 
ported this species upon the sabellid, Fota- 
milla myriops. Berkeley and Berkeley (1952) 
do not list this species for the Puget Sound 
area but do list Potamilla neglecta, which is 
one of the hosts for Prohoscidactyla occidentalism 
the third species of this report. Prohoscidactyla 
flavkirrata occurred on two species of sabel- 
lids in the Puget Sound area, namely Schizo- 
hranchia insignis and Pseudopotamilla ocellata. 
Ten genera of sabellids were reported by 
