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PACIFIC SCIENCE, Vol. XX, July 1966 
found. The average number of worms in in- 
fected hosts was 5, the maximum was 30. The 
population of parasites, therefore, was suffi- 
ciently dense to provide numerous larvae in the 
water. All of the mature female worms were 
filled with larvae in all stages of development, 
including actively moving forms ready to leave 
the mother. The absence of parasites in the 
copepods is difficult to explain, since copepods 
are presumably the intermediate hosts. The sea- 
son of the year might be a factor, but probably 
not enough copepods were examined. 
There is no evidence that the worms are 
pathogenic to the host. Any consideration of 
parasite-host relationships should include at 
least a notice of the total parasite fauna. Other 
parasites found in the 50 hosts examined were: 
On the gills: Trichodina (closely similar to 
Paratrichodina obit qua ) , Gyrodactylus sp., 
metacercariae, and a microcotyline mono- 
genetic trematode. 
In the gall bladder: the myxosporidians, 
Zschokkella and Ceratomyxa. 
In the muscles: metacercarial cysts. 
Fig. 7. Posterior end of a male worm, lateral 
view. 
In the digestive tract: metacercarial cysts (in 
only one host). 
The paucity of parasites in the intestine is 
probably correlated with the host’s habit of 
feeding primarily on an organic detritus. Spiro- 
camallanus istiblenni obviously does not have 
much competition for space and nutrients except 
that provided by its host. 
In 1952 Olsen erected a new genus, Spiro- 
camallanus, to accommodate 17 species of Pro- 
camallanus characterized by spiral thickenings 
inside the buccal capsule. Ali (i 960 ) has 
pointed out that within the genus Procamallanus 
there are species with "comb-like chitinous 
plates,” finger-like projections, "golf club 
shaped projections,” "knob-like structures,” 
transverse thickenings, and other modifications 
of the buccal capsule wall. Ali believes that the 
use of spiral thickenings as the sole basis of 
distinction is not warranted, and that the 
spicule pattern in the male offers morphological 
variations that are more sharply defined. Some 
worms do not possess spicules, in others there 
are one or two, and in the latter group the 
