References:

Type locality: off coast of Nice (France).

Depth range: 1 - 110 m.
Range: Late Paleocene - Holocene

Thecidea mediterranea Risso, 1826, p. 394
Thecidea spondylea Scacchi, 1836
Terebratula (Thecidea) mediterranea (Risso) : Reeve, 1861
Thecidium mediterraneum (Risso) : Lacaze-Duthiers, 1861

See Emig (2012)

After Logan (1979) modified:

Adult shell rarely exceeding 3 mm in length. Shell out!ine usually triangular, but may be irregular. Shell biconvex, dorsal valve almost flat, thin, circular to semi-circular in shape. Shell pale brown in colour, smooth or with irregular concentric growth lamellae, punctate. Hinge !ine straight. Anterior commissure rectimarginate to slightly unip!icate. Beak of ventral valve pointed, without foramen but with well defined attachment scar. Ventral cardinal area flat, triangular, with flat triangular pseudodeltidium.
Ventral valve papillose, hinge line straight, furnished with hinge teeth; interior of beak hollow, with small median septum supporting hemispondylium projecting anteriorly as 2 prominent prongs, this muscle platform (occasionally median-keeled) acting as a base for columnar muscles to the dorsal valve.
Dorsal valve hinge line with sockets flanking prominent subrectangular, slightly concave cardinal process. Papillose margin of valve produced posteriorly into bridge in front of cardinal process and anteriorly into an ascending trifurcating median septum, which ends posteriorly in a thin pointed and upraised median lobe and two broader and blunted lateral lobes, con cave in profile. Edges of all three ascending lobes raised from valv floor and denticulated. Cavities between papillose margins, bridges and septum lobes occupied by partially denticulated descending double lamella forming wide crescents, arcuate to left to right.
Lophophore ptycholophous, with median and two lateral invaginations. Brood pouch present in adult females, which exhibit a notched bridge for passage of pair of modified lophophore filaments. Spicules present in mantle only.

Lacazella australis (Tate, 1880)

Type locality: "Superior beds" (Miocene: Balcombian), Muddy Creek, Victoria, Australia.

Range: Early Miocene

Thecidium australe Tate, 1880 p. 166
Thecidellina australis australis (Tate): Pajaud, 1970, p. 238

Shape variable, subcircular in smaller specimens, elongate in larger specimens. Attachment scar well-developed, irregular in shape. Ventral valve with raised pseudodeltidium. Outer margins of ventral interarea poorly defined. Cardinal teeth robust. Hemispondylium well developed. No median septum. Cardinal process broad, projects strongly anteriorly.

Diagnosis facsimile of Tate (1880)

Type locality: Mauritius
Depth range: ? m

This species has a remarquable resemblance to the preceding [= Lacazella mediterranea], with which it has been confounded, but differs by having in the apical cavity of the attached valve instead of a platform supported by a septum, only two long, slender, excavated, upturned pro cesses completely isolated medially, with no sign of a septum. The outer surface is minutely reguliarly granular. In other respects it agrees closely with L. mediterranea.

Type locality: Station 52, east of Cabo Samaná, Dominican Republic in Cooper, 1977 p. 27 (not off Rio Bueno, north central Jamaica, as stated by Cooper, 1977, p. 133)
Depth range: 25 - 60 m
Range: Miocene - Holocene

Small Lacazella with hemispondylium attached to the valve floor and the ascending apparatus narrow anteriorly and with smooth margins.

Small, transversely oval in outline with the maximum width at about midvalve; sides somewhat narrowly rounded; anterior margin gently rounded to nearly straight; hinge narrower (about hall) than the valve width, beak somewhat narrowly pointed; pseudodeltidium (?) narrow, not strongly convex; shell substance punctate. Ventral valve moderately convex and with a large area of attachment; anterior half somewhat flattened and moderately geniculated. Dorsal valve moderately swollen medially and with the sides and anterior somewhat tlattened.
Ventral valve interior with strongly papillose inner rim but most of the valve floor smooth to obscurely radiately striated; teeth smalI; hemispondylium narrow, not complete anteriorly and consisting of two separate thin plates bounding a narrow chamber with strong median septum not reaching the anterior margin of the structure; hemispondylial plates pointed distally.
Dorsal valve interior with tlattened and strongly papillose rim; ascending apparatus narrow and deep anteriorly and with smooth margins; descending apparatus (interdorsallobe) forming a wide and smooth margined crescent; median ridge of the ascending apparatus not grooved and not splnose; median elements of the descending apparat us short and bluntly pointed; bridge broad and with a fairly deep and wide marsupial notch. Cardinal process rather narrow and fairly long.

Lacazella novazelandiae Hiller, 2011

Type locality: Waitiiti Formation, Taita Stream, Waimamaku Valley, New Zealand.

Range: Early Miocene

Small Lacazella with tiny teeth and subdued papillation in valve interiors. Dorsal interior with relatively narrow median septum with smooth margins..

Hiller (2011) pointed out: