THE ' r A S M A NIA N N AT U R A LIST. 
Division b.— Siphonida, Integro pcilliata. 
1. The Chamidae, represented by the reef-dwelling Ckatna. 
2. The Tridacnidae. whose sole genus, Tridacna , contains the 
largest species of the whole class of bivalves, the shells sometimes 
measuring two feet across. 
3. The Cardiadae or Cockles, usually found embedded in mud 
(Fig. 30). 
4. The Lucinidae , in which the valves are nearly circular, and 
frequently prettily sculptured on the outside (Fig. 27). 
5. The Cycladidae. Some genera belonging to this family, small 
thin shells, are to be found in many of our ponds and streams. 
6 and 7. The Astartidae and Cyprinidae belong to the northern 
hemisphere. 
Division c. — Siphonida, Sinu-palliata . 
1. The Vctieridae . The hard, solid shells of this family are, for 
elegance of form and beauty of colour, amongst the most attractive a 
collector can possess. Amongst others we have one beautiful species, 
whose ridges in fine specimens develop into elevated pink frills. 
(Fig. 24). 
2. The Mactridae are somewhat triangular in shape, with hard, 
solid shells, and may at once be recognised by the pit for the hinge 
ligament (Fig. 28). 
3. The Tellenidac comprise some of the most delicately tinted, 
both externally and internally, of all shells. In some, coloured bands 
radiate from umbones, and well bear out the fanciful name of ‘ Sun¬ 
set shells ’ bestowed upon them. Their valves are generally much 
compressed. 
4. The Solenidae or ‘ Razor shells J are readily recognised by the 
extreme length of the valves in proportion to the width, and also by 
their gaping at both ends (Fig. 23). 
5. The Myacidae . Not represented here. 
6. The Anatinidae have thin, often inequivalve pearly shells ; one 
member of the family (Cochlodesma Angasi, Fig. 26) is a conspicuous 
object on some of our beaches. 
7. The Gastrochffnidae embraces two genera ( Gastrochctna and 
Saxicava) of boring Mollusca, and also the remarkable tube-like 
‘ Watering-pot shell,’ Aspergillum , which is hardly recognizable as a 
bivalve at all. 
8. The Pholadidac concludes the list of bivalves, and comprise 
the rock-boring Pkolas (Fig. 32) and the wood-boring Teredo or 
‘Ship-worm,’ which is so destructive to the piles of wharves and 
jetties. 
Although the Brachiopoda or ‘ Lamp shells ’ are not true Mollusca, 
thc> are not very far removed from them, and are so often to be found 
