Fig. 37.
Ship-worm
(Teredo norvegica).
Case 202.
a, animal, removed from its shelly tube: p, p, pallets; s, exhalant siphon; s′, inhalant siphon.
b, c, different aspects of the shell.
These animals are most destructive to ships, piers, etc.; and wood, which is not protected by metal, when once attacked, is soon riddled through and through. They work either with or across the grain, and although the holes may be all but touching, they seldom appear to run into one another.
Fig. 38.
Watering-pot Shell
(Brechites vaginifer).
Case 204.
a, bivalve shell of the very young animal.
The “Watering-pot shell” (Brechites), of the family Clavagellidæ, is a very remarkable structure, and unlike the shell of an ordinary bivalved mollusc. On looking carefully, however, near the perforated end (the rose), two small valves will be seen imbedded in the surface. They are found with the rose downwards buried in mud or sand at low water on the shores of the Indian and Pacific Oceans.
Septibranchia. (Fig. 25, D.)
Case 204.
The members of this order differ from other Lamellibranchs in having the gill-plates represented by a muscular septum. They are provided with two respiratory siphons and two adductor muscles, and the edges of the mantle-lobes are connected at three points. The families Poromyidæ, and Cuspidariidæ, constitute this order. The species are all small, without colour-markings, are world-wide in their distribution and occur at all depths.
Class V.—CEPHALOPODA.[[9]]
