38 
WEST WING. 
by models of Trichina, and the anatomical structure of various 
other forms is shown by the aid of diagrams. Case 3 contains 
the free-living Terrestrial and Marine Worms, the Leeches, and 
Gephyreans. 
Shell Gallery. V. A large gallery devoted to the extensive division of 
MoLLUSCA, the exhibition of which is however mainly restricted 
to their shells. In some cases the form of the animal itself is 
shown either by specimens in spirit or by means of models. 
The first table-case on the left as the gallery is entered contains 
the Argonauts, the beautiful pearly Nautilus, the rest of the 
Cephalopods (Octopus, Squids, &c.), the fragile glassy Pteropods, 
and the Cones, one of the most beautiful groups of the Gastro- 
pods, a division which includes Snails, Whelks, Slugs and all 
those Molluscs which crawl upon the under surface of their body. 
They are contained in cases 1-17. The Bivalves or those 
MoUusca which, like the Cockle and Oyster, are protected by a 
shell formed by two pieces or valves, are arranged in cases 
17-26. The most generally known of this division are the 
Venus-shells (case 17) ; the Cockles (case 19) ; the Giant Clam, 
sometimes weighing as much as 500 lbs. each (case 20) ; the 
Piddocks and Teredos, borers in wood and stone (case 19) ; 
the Eazor-shells (case 20); the Pinnas (case 24) ; Scallops 
and Thorny Oysters (case 25) ; and the True Oysters (case 25). 
A fine series of very large shells and some interesting 
Cephalopods in spirit occupy four upright cases at the ends of the 
room ; and near the entrance to the gallery are placed some 
small table-cases, containing series of the eggs of Mollusca and 
of their opercula or lids by means of which the opening or mouth 
of the shell is closed in some forms ; also specimens illustrating 
the formation of pearls, and other special points of interest 
connected with the group. 
A special guide-book to the Shell and Star-fish galleries is 
published for the use of visitors, and guides to the remaining 
galleries are in preparation. 
Gallery of Cetacea. 
Cetacea or Approached by a staircase, leading from the last (or western- 
GaiTery. most) of tlio passages which connect the bird gallery witli the 
