ABSTRACT
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 Tubinicella is almost equally allied to the latter genus, to Platylepas, and to Coronula. As the shell of Tubicinella increases in diameter, from the growth of the radii, the opercular membrane lining the sheath is necessarily split along the six lines of suture, in the same manner as is the membrane externally investing the shell. The opercular membrane at the summit of the shell, in Tubicinella, is folded in concentric lines, and so deeply, that the basal edges of the opercular valves are generally hidden. In all these characters the muscles of Tubicinella and Coronula resemble each other.
