This genus is closely allied to [Coronula], and perhaps De Blainville was right in uniting them. But [Coronula], as it now stands, is so natural a genus, that it seems a pity that a form so entirely different in general aspect, as [Tubicinella], should be forced into it. The main difference between these genera consists in the walls being here not folded, in the simpler radii, and in the general shape of the shell and of the included animal’s body; but there are many other minor points of difference. The most novel character in [Tubicinella] consists in the shell being lined almost close down to the basis by the opercular membrane. In the opercular membrane thus forming a long tube, and in the general shape of the animal’s body, we shall presently see that [Tubicinella] is closely related to [Xenobalanus]. In numerous other respects [Tubicinella] is almost equally allied to the latter genus, to [Platylepas], and to [Coronula]. Finally, several points of structure indicate that [Tubicinella] may be considered as a [Coronula], with the shell much simplified in structure.
1. [TUBICINELLA] TRACHEALIS. Pl. [17], fig. [3 a]-[3 c].
LEPAS TRACHEALIS. Shaw. Nat. Miscell. (1789-1813), vol. 17 (1806?) tab. 726.
---- TRACHEÆFORMIS. Wood. General Conch. (1815), tab. 4, fig. 1-3.
TUBICINELLA TRACHEALIS. J. E. Gray. Annals of Philosophy, (new series), vol. 10, (1825.)
---------- MAJOR ET MINUS. Lamarck.[127] Annales du Mus. Nat., tom. 1 (1802), Tab. 30, fig. 1-2.
---------- BALÆNARUM. Lamarck. Animaux sans Vertèbres, (1818).
---------- ---------- Chenu. Illust. Conch. (Plate).
---------- ---------- Sowerby. Genera of Recent and Fossil Shells (Plate).