46 
produced internally for tlie attachment of the muscle fibres, and ■ 
are, moreover, firmly welded to the shell. 
The tendons and other internal prolongations of the cuticle 
arises from pocket -like invaginations of the epithelium, and are 
shed with the rest of the cuticle. It would thus appear that the 
new tendon cannot arise until the old one is shed, and this may 
account for the paralysed condition of the limbs for a while after 
casting. 
The exuviated cuticle of the chela of a lobster, showing the large adductor and abduc j 
“tendons” of the dactylopodite, and the smaller ‘\tendons” of the other segments ( 
The setae which are to be seen on the surface of the new shell 
immediately after sloughing deserve a word. In each case a papilla 
is to be seen, formed of epithelium, projecting more or less into the 
cavity at the base of the seta. Each seta consists of a hollow spine 
with or without barbs at the distal extremity. At the base it 
expands and occupies a wide space in the pigmentary layer of the 
cuticle. The spine and the lining of the cavity in the pigmentary 
layer are produced from the outer layer. As the third layer is pro- 
duced the papilla projecting into the seta forms a tube which on 
completion of the shell preserves the communication between the 
interior of the spine and the epithelium. Simple cuticular prolon- 
gations also occur, and it is to be presumed with Vitzou® that they 
have a definite relation with the underlying epithelium. 
3. — Vitzou: Recberches sur la structure et la formation des teguments chez les Crustacfis 
Dgcapodes. Arch, de Zool. Exp6r. et Gtoeral. 1882. 
