246
MARINE MOLLUSCS AS HOSTS FOR SYMBIOSES
of prepharynx ; suckers about the same size, 0.06 mm in diameter, with
anterior sucker slightly larger ; small glands along posterior margin of
anterior sucker ; ventral sucker in center of body ; prepharynx, pharynx,
and short esophagus present ; intestinal caeca reaching to near posterior
end of body ; excretory vesicle large and pear-shaped, sometimes
bilobed ; two testes, one on each side, midway between ventral sucker
and posterior end of body ; ovary in front of right testis.
Life cycle. According to Lebour (1911),
The final host is the catfish Anarrhichas lupus and it is very probable that
there is no (second) intermediate host, the fish swallowing the Buccinum
undatum with the contained rediae, the cercaria thus getting into the intestine without aid of another host. I have never seen any trace of cysts in
the catfish.
Whether this is the case remains to be determined experimentally.
Lebour was apparently unaware that Stafford (1904) has described
what she considered to be the adult of her cercaria in Anarrhichas lupus
under the name Neophasis pusilla, which, according to the rules of
nomenclature, is the valid one.
Other information. Lebour (191 1) has reported that the cercariae
(probably also the rediae) are found during the spring and summer but
never in the winter. This suggests that parasitized Buccinum undatum
lose their infections preceding or during the cold months and a t the
same time are not reinfected. Reinfection would appear to occur
during later winter or early spring.
33. Cercaria neptuneae sp. inq. Lebour, 1911. (Figs. 155 and 156)
superfamily Allocreadioidea ; family Allocreadiidae)
(Superorder Epitheliocystidia; order Plagiorchiida; suborder Plagiorchiata;
Cercaria neptuneae develops in rediae found in the digestive gland
of Neptunea antiqua and Buccinum undatum “brought in by the
Cullercoats [northeast England] fishing boats. . . in July ” (Lebour,
1911).
Description of stages in mollusc. Redia (Fig. 155) colorless, 2 mm
or more in length; with pharynx, 0.04 mm long, and very short
intestinal caecum, not longer than pharynx ; no collar or ambulatory
buds ; contains cercariae a t various stages of development. Cercaria
(Fig. 156) covered with small cuticular spines ; 0.4 mm long (without
tail), 0-10 mm wide (highly variable) ; tail straight, exceedingly large
and thick, about 0.26 mm long x 0.049 mm wide; anterior sucker
0-033 mm in diameter; prepharynx 0.06 mm long, pharynx 0.03 mm
long, rest of alimentary tract not seen ; two large eye-spots immediately
MARINE MOLLUSCS AS HOSTS FOR SYMBIOSES
of prepharynx ; suckers about the same size, 0.06 mm in diameter, with
anterior sucker slightly larger ; small glands along posterior margin of
anterior sucker ; ventral sucker in center of body ; prepharynx, pharynx,
and short esophagus present ; intestinal caeca reaching to near posterior
end of body ; excretory vesicle large and pear-shaped, sometimes
bilobed ; two testes, one on each side, midway between ventral sucker
and posterior end of body ; ovary in front of right testis.
Life cycle. According to Lebour (1911),
The final host is the catfish Anarrhichas lupus and it is very probable that
there is no (second) intermediate host, the fish swallowing the Buccinum
undatum with the contained rediae, the cercaria thus getting into the intestine without aid of another host. I have never seen any trace of cysts in
the catfish.
Whether this is the case remains to be determined experimentally.
Lebour was apparently unaware that Stafford (1904) has described
what she considered to be the adult of her cercaria in Anarrhichas lupus
under the name Neophasis pusilla, which, according to the rules of
nomenclature, is the valid one.
Other information. Lebour (191 1) has reported that the cercariae
(probably also the rediae) are found during the spring and summer but
never in the winter. This suggests that parasitized Buccinum undatum
lose their infections preceding or during the cold months and a t the
same time are not reinfected. Reinfection would appear to occur
during later winter or early spring.
33. Cercaria neptuneae sp. inq. Lebour, 1911. (Figs. 155 and 156)
superfamily Allocreadioidea ; family Allocreadiidae)
(Superorder Epitheliocystidia; order Plagiorchiida; suborder Plagiorchiata;
Cercaria neptuneae develops in rediae found in the digestive gland
of Neptunea antiqua and Buccinum undatum “brought in by the
Cullercoats [northeast England] fishing boats. . . in July ” (Lebour,
1911).
Description of stages in mollusc. Redia (Fig. 155) colorless, 2 mm
or more in length; with pharynx, 0.04 mm long, and very short
intestinal caecum, not longer than pharynx ; no collar or ambulatory
buds ; contains cercariae a t various stages of development. Cercaria
(Fig. 156) covered with small cuticular spines ; 0.4 mm long (without
tail), 0-10 mm wide (highly variable) ; tail straight, exceedingly large
and thick, about 0.26 mm long x 0.049 mm wide; anterior sucker
0-033 mm in diameter; prepharynx 0.06 mm long, pharynx 0.03 mm
long, rest of alimentary tract not seen ; two large eye-spots immediately