THOMPSON: SNAIL GENUS MARSTONIA


Taylor 1966, Cincinnatia Pilsbry 1891, Fontelicella Gregg and Taylor 1965,
Birgella F. C. Baker 1926, Rhapinema Thompson 1969, Notogillia Pilsbry
1953, Spilochlamys Thompson 1968, and perhaps Pyrgulopsis Call and Pilsbry
1886. The reproductive anatomies of these genera remain unstudied except
for the verge. I examined internally males of all but Fontelicella and Pyrgulop-
sis. The males are alike in having (1) a bilobed verge with a slender terminal
penis off the right margin; (2) a single duct, the vas deferens, within the verge;
(3) various superficial apocrine glands on the verge, apical crest, and/or
penis; (4) the verge innervated by the right pleural ganglion; and (5) a con-
nective absent between the vas deferens and the mantle cavity. I have ex-
amined cursorily the female reproductive systems of Notogillia, SpilochlainIs,
Rhapinema, Cincinnatia, and Birgella, and find they are basically similar to
Marstonia. The females of these genera agree in having (1) a thick, glandular-
walled loop in the oviduct I beside, and mesad to, the posterior pallial oviduct;
(2) a gonopericardial duct; (3) a single seminal receptacle (SR 2) at the base of
the oviduct loop; (4) a bursa copulatrix that has a duct partially imbedded in
the posterior pallial oviduct; and (5) a closed oviduct II within the anterior
pallial oviduct.
 The oldest and only group name proposed for the North American bi-
lobed-verge genera is the Nymphophilinae Taylor 1966. Other North Ameri-
can hydrobine genera have an unlobed verge and are placed in different sub-
families. These other genera remain unstudied internally and further com-
ments on similarities or differences are not possible.
 Radoman (1973) divided the Balkan hydrobine snails into a number of
families and subfamilies. The Nymphophilinae of North America are equiva-
lent to Radoman's Orientaliidae, with its subfamilies Orientaliinae, Hora-
tiinae, Sadlerianinae, Pseudohoratiinae, Islamiinae, Graecoanatolicinae, Pyr-
gulinae, Chilopyrgulinae, and Ochridopyrgulinae. These subfamilies are
based on the numbers, position, and development of the seminal receptacles
and the bursa copulatrix. The Nymphophilinae is most like the Pseudohora-
tiinae in having a single seminal receptacle 2 and a normal bursa copulatrix.
 I feel that greater emphasis is placed on these divisions (families and sub-
families) of the Balkan hydrobiids than is currently justified, especially since
so little is known of the anatomies of the hydrobiids from the rest of the world.
In any event, Nymphophilinae Taylor 1967 is equivalent to and predates Ori-
entaliidae Radoman 1973 and its subordinate groups.
 Marstonia is more similar to North American hydrobiid genera than to any
European genus. It is unique among North American groups in having a rela-
tively simple glandular pattern on the verge and a short terminal penis. Other
genera, except Rhapinema, have elaborate patterns of many glands. Rhapi-
nema, like Marstonia, has a single large gland (the apical gland) on the apical
lobe, but it differs by having both a long, slender flagellar penis and a large,
globose shell with a thick rolling parietal callus and columella.
 The shell of Marstonia is characterized by its generally narrow shape, gen-