228
MARINE MOLLUSCS AS IIOSTS FOR SYMBIOSES
absent ; pharynx 0.020-0.025 mm in diameter ; esophagus short ;
intestinal caeca large, with walls comprised of polygonal cells, reaching
level of anterior one-third of ventral sucker; small deeply staining
spiral coil maintains a constant lumen between pharynx and esophagus ;
two pairs of cephalic glands at posterior level of pharynx, ducts leading
to anterior body terminal ; excretory vesicle Y-shaped with extremely
fine stem (V-shaped according to Uzmann) and arms recurved around
intestinal caeca ; stem extends and enlarges in tail, bifurcates, branches
terminating at tips of furcae; flame-cell pattern 2[(2 + 2 + 2) +
Life cycle. The life cycle of C. myae remains unknown. The cercariae
are capable of swimming. While swimming, the posterior portion of
the body is bent ventrally in apposition to the anterior portion. The
tail lashes vigorously and the spring-like action produced when the
body straightens out makes this cercaria a very active swimmer. It
does not encyst ectopically and becomes moribund after about 12 h.
Uzmann (1952) has suggested a similarity between this cercaria
and Sinitsin’s Cercaria discursata which Allison (1943) has suggested may
belong to the family Brachylaemidae but Stunkard and Uzmann
(1958) have expressed the opinion that C. myae is a gymnophallid.
Ecology. C. myae is a rare parasite. Uzmann (1952) found only five
out of over 1 000 clams at Newburyport, Massachusetts, to be infected.
Stunkard and Uzmann (1958) only found three out of over 1 000 clams
from Boothbay Harbor, Maine, to be infected, and I found one infected
M . arenaria out of 800 examined in Rhode Island.
Pathology. Uzmann (1952) has stated that : “ There is histological
evidence of partial to complete sterilization (of parasitized clams).” I
have been able to confirm this in addition to finding almost complete
destruction of the digestive gland tubules.
(2 + 2 + 211.
20. Bacciger bacciger (Rudolphi, 1819). (Figs. 139 and 140)
(Superorder Anepitheliocystidia; order Strigeatoidea; suborder Azygiata;
superfamily Fellodistomatoidea; family B’ellodistomatidae)
The adult of Bacciger bacciger was originally discovered by Rudolphi
(1819) in marine fish. Nicoll(l914) redescribed the adult and placed it in
the genus Bacciger. Although considered a member of the family
Cryptogonimidae by Yamaguti (1958), I am in agreement with Dawes
(1946), Cable (195413) and Skrjabin (1957) that it is a member of the
Fellodistomatidae. The definitive host includes Atherina hepsetus, A.
presbyter and A. boyeri. Its cercaria was first found by Lespes (1857)
who, unaware of its relationship with the adult, named it Cercaria lata.
MARINE MOLLUSCS AS IIOSTS FOR SYMBIOSES
absent ; pharynx 0.020-0.025 mm in diameter ; esophagus short ;
intestinal caeca large, with walls comprised of polygonal cells, reaching
level of anterior one-third of ventral sucker; small deeply staining
spiral coil maintains a constant lumen between pharynx and esophagus ;
two pairs of cephalic glands at posterior level of pharynx, ducts leading
to anterior body terminal ; excretory vesicle Y-shaped with extremely
fine stem (V-shaped according to Uzmann) and arms recurved around
intestinal caeca ; stem extends and enlarges in tail, bifurcates, branches
terminating at tips of furcae; flame-cell pattern 2[(2 + 2 + 2) +
Life cycle. The life cycle of C. myae remains unknown. The cercariae
are capable of swimming. While swimming, the posterior portion of
the body is bent ventrally in apposition to the anterior portion. The
tail lashes vigorously and the spring-like action produced when the
body straightens out makes this cercaria a very active swimmer. It
does not encyst ectopically and becomes moribund after about 12 h.
Uzmann (1952) has suggested a similarity between this cercaria
and Sinitsin’s Cercaria discursata which Allison (1943) has suggested may
belong to the family Brachylaemidae but Stunkard and Uzmann
(1958) have expressed the opinion that C. myae is a gymnophallid.
Ecology. C. myae is a rare parasite. Uzmann (1952) found only five
out of over 1 000 clams at Newburyport, Massachusetts, to be infected.
Stunkard and Uzmann (1958) only found three out of over 1 000 clams
from Boothbay Harbor, Maine, to be infected, and I found one infected
M . arenaria out of 800 examined in Rhode Island.
Pathology. Uzmann (1952) has stated that : “ There is histological
evidence of partial to complete sterilization (of parasitized clams).” I
have been able to confirm this in addition to finding almost complete
destruction of the digestive gland tubules.
(2 + 2 + 211.
20. Bacciger bacciger (Rudolphi, 1819). (Figs. 139 and 140)
(Superorder Anepitheliocystidia; order Strigeatoidea; suborder Azygiata;
superfamily Fellodistomatoidea; family B’ellodistomatidae)
The adult of Bacciger bacciger was originally discovered by Rudolphi
(1819) in marine fish. Nicoll(l914) redescribed the adult and placed it in
the genus Bacciger. Although considered a member of the family
Cryptogonimidae by Yamaguti (1958), I am in agreement with Dawes
(1946), Cable (195413) and Skrjabin (1957) that it is a member of the
Fellodistomatidae. The definitive host includes Atherina hepsetus, A.
presbyter and A. boyeri. Its cercaria was first found by Lespes (1857)
who, unaware of its relationship with the adult, named it Cercaria lata.