XXV1 INTRODUCTION. 
this the animal remains for a considerable time in a 
languid state, and is quite transparent and colourless.” 
The new creature is a perfect representation of the old 
one, slightly enlarged. According to our observations, 
every hair is produced complete. We have often seen 
them, convoluted and bent up within the old case, from 
which they only wanted to be freed to assume the erect 
position of the perfect hair. It has, however, contrary to 
our anticipation, appeared that all the hairs are not de- 
veloped within each corresponding one. We have fre- 
quently observed them as a second armature, independent 
of the old one. This remark is particularly distinguish- 
able in the teeth that fringe the first two siagnopoda. 
These have generally a dentated and forked character, 
which might be injured in their removal from the old and 
hard tissue of the rejected skin, an accident that not 
unfrequently befalls the branchial sacs, which are occa- 
sionally torn off and retained behind in the old case. 
The power of Crustacea to throw off any of the limbs 
upon receiving an injury, and sometimes in consequence 
of fright, is well known in relation to the higher orders. 
The manner in which this is done has been described by 
Dalyell, Goodsir, and ourselves. It certainly is a remark- 
able power and law of reproduction, and which always 
takes place at the same homotypical position in every 
limb—that is, between the coxa and the next succeeding 
joimt. The wound that is caused by this sudden rupture 
is simultaneously glazed over by a thin membrane, which 
must be very suddenly formed, and probably is the ampu- 
tating power. Observers have very generally added as an 
appendage to the above interesting fact, that it is exceed- 
ingly fortunate that there is this power of voluntary 
amputation of the limbs, for otherwise, in consequence of 
the non-contractile character of the dermal covering, the 
