Thylaeodus semisurrectus
(Bivona-Bernardi, 1832)
Mediterranean, Gibraltar area.
Suspension feeder in the circalittoral and deeper.
Original taxon: Vermetus semisurrectus.
 
« Shell solitary, cylindrical, horny, anteriorly elongated, erect, often interrupted by varices, posteriorly affixed and twisted. Basal sculpture composed of granular, elevated longitudinal series, which make the first whorls rough (rarely with one of these striae higher than the others), then entirely devoid of sculpture with the part of the tube erect, and surrounded by very thin growth striae. Colour horny. » – T. A. di Monterosato: “Monografia dei Vermeti del Mediterraneo”, Bullettino della Società Malacologica Italiana vol.17, Pisa 1892, p.40.

100m deep, Saronic Gulf, Central Greece. 28,9mm.
Synonym sequenzianus (sic) Aradas & Benoit, 1874, who write that it is similar to semisurrectus « sed gregaria saepe ».
Above, the species in Monterosato’s vermeti, plate VI.
The sculpture along the coiled whorls: « granular, elevated longitudinal series » surrounded by thin growth marks.

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