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TLAXOBBIS. 125
252. Planorbis (Segmentina) umbilicalis (Benson).
Planorbis {Seginentind) umbilicalis (Benson), J. A. S. B. v, 1836,
p. 741 ; A. -M. N. II. ser. 2, v, 1853, p, 351; Martens, Mai.
Bliitt. xiv, p. 216; H. &T., C. I. pi. 40, figs. 7-9; Sowerby
in. Reeve, Conch. Icon, xx, pi. 10, fig. 77; Clessiu, in Ooncli.-
Cab. 1884, p. 136, pi. 15, fig. 6.
Original description :—Testa quasi dextva luteo-coriiea, polita,
leviter radiato-striata, iufra excavato-depressa, anfractibus omnibus
versus umbilicum profundum spectantibus, ultimo interiores pene
tegente; supra convexa versus apicem plaiiata, apice concavo,
omuibus anfractibus satis apparentibus ; periplioeria obtuse
angulata.
The dimensions as given by Clessin are as follow :—
Alt. 2, diam. 8'5 mm.
Hah. Syihet.
2.53. Planorbis (Segmentina) trochoideus (Benson).
Planorbis (Segmentina) trochoideus (Benson), J. A. S. B. v, 1836,
p. 742 (Glean. Scien. Calcutta, i, pi. 8, flo-. 10) ; A. M. N. H.
ser. 2, V, 1850, p. 352 ; H. & T., C. I. pi. 39, figs. 4-0;
Sowerby in Reeve, Conch. Icon, xx, pi. 9, fig. 70; Clessin, in
Conch.-Oab. 1886, p. 225.
Original description:—Testa quasi dextra diaphaua, subtrochiformi,
supra glabra, rotuiidato-convexa, apice concavo-depresso
quasi umbilical!; anfractibus omnibus parum apparentibus, sutura
exciivata divisis ; infra radiatim striata, truncata, planata, umbilico
confracto. Anfractu ultimo majori reliquos amplectente, supra
pene, infra omnino obtegente ; periphseria acuta.
Alt. scarcely 2, diam. 3 mm.
Hah. Barraekpore.
254. Planorbis (Segmentina) grun^ri (Clessin).
Planorbis (Segmentina) gruneri (Clessin), in Conch.-Cab. 1884,
p. 148, pi. 21, fig. 9.
Original desei-ipttion :—Testa depressa, supra centro paululum
concave, .siibtus subplauata, nitidula subtilissime irregulariter
striata, diaphana. cornea ; anfr. 4^ lenteet regulariter accrescentes,
depresso-ovati, utrinque convexiusculi ac sutura profunda separati;
ultimus penultimo t'ix duplo latior; apertura obliqua, ovata;
peristoma acutum, marginibus disjunctis ; niargine superiore
paululum producto.
Alt. 8, diam. 5 mm.
Hah. India; Singapore.