73 
mOOM XU., Xin.2 NATURAL HISTORY. 
Cases 17 and 18 contain tlie Muscles^ {Mytili,') Horse 
Muscles^ (Modiolu, Pinna, and Avicula,) the animals of 
which are peculiar for the foot being smalh and fur¬ 
nished with a tuft of fibres at its base in fronts by which 
the animal fixes itself to rocks^, &c. This beard, as it is 
tjalled in the last genus, issues out of a groove in the front 
of the right valve. The Pinnae, like the Pond Muscles, 
difiPer according to the place they inhabit. Those which 
live in smooth water are thin and covered with rows of 
small scales, while those that are found in rough water are 
thick and rugose. 
Then follow the genera Area, Pectwnculus and Nucula, 
the animals of which have a large foot divided at the end, 
and the hinge formed of many interlocking teeth. In Area 
the end of the foot forms a glutinous secretion, which at 
length hardens, by which the animals attach themselves to 
rocks, &c. and the shell is rhombic. In Peetuneulus, the® 
shell is orbicular, and the hinge line curved, while in Nuenla, 
the hinge line is angular, with the cartilage placed in a 
pit at the angle. 
Lastly, follow the shells of the Branchiopodous Mol- 
lusca, which have two ciliated arms, one placed on each 
side of the mouth. Of these, only two genera are found 
in Britain, viz. Terehratula and Criopus; the first is 
affixed by a tendon passing out through a hole in the upper 
valve; the latter is attached by the outer surface of its 
ander valve. 
THIRTEENTH ROOM. 
The upright glazed Cases round the room contain 
the general collection of Birds. 
Cases 1 to 12 contain the Raptorial or Birds of Prey, 
the Accipitres of Linnseus, which constitute the first Order. 
They are characterized by strong feet with sharp claws, 
and a powerful bill, the latter covered at the base by a 
naked skin, or cere ; their stomach is almost entirely mem¬ 
branous, and sternum broad, giving attachment to the 
muscles of their long wings. Some of them feed chiefly 
by day; their eyes are placed on the side of their head, 
and the nostrils exposed, as in the family of Condom, 
(Cases 1 and 2,) found principally in America, whieh 
have naked heads and longitudinal nostrils: as the Condor, 
or Great Vulture of the Andes ; the Californian Vulture, 
K 
