[132] Χαμαι [Greek: Chamai], on the ground, and σιφων [Greek:
siphôn], a tube.
_Compartments four, with the sutures often much obliterated: basis
membranous._
_Distribution_, Australia, China (?). Attached to littoral shells and
rocks.
The two species united under this genus agree in having only four
compartments, and in these having a strong tendency to become
confluent; but they resemble each other hardly in any other respect,
more than do all the species of the present sub-family. _Chamæsipho
columna_ differs from all the other Chthamalinæ in the structure of
its second pair of cirri, and _C. scutelliformis_ differs from all in
its shell,--namely, in the small size of the rostrum, with its alæ
but little developed, and in the very peculiar apertures in the three
other compartments. Hence this genus can hardly be considered a very
natural one, though I could not introduce the two present species into
Chthamalus, or into any other genus, without doing still more violence
to the principles of classification followed throughout this work.
Chamæsipho bears nearly the same relation to Chthamalus, as Tetraclita
and Elminius do to Balanus.