170 Exuviation in Shrimps and Lobsters. 
mixed upon the sides with golden yellow, and showing indications 
of darker transverse bands upon the back ; upon theopercle a spot of 
blue, continued towards the eye ; fins rosy pink mixed with yellow. 
Upon the anterior part of the dorsal fin a deep black spot or blotch, 
occupying the greater part of the membranes of the three first rays ; 
another upon the upper margin of the base of the caudal fin. These 
spots were similar in size and situation in Dr Johnston's spe- 
cimens, and they continue unaltered in the spirits, although the other 
colours have faded to a pinkish brown. 
As the specific title of Cornubicus has been applied to the other 
species, and described as the Goldsinny by various writers subse- 
quent to Pennant, it is proposed to designate the present species as 
the Labrus (Crenilabrus) rupestris, (Jago's Goldsinny,) to which 
the following synonyms may be appended. 
Goldsinny, Ray's Syn. Av. et Pise. App. Catalogus quorundum 
rariorum, c. D. Georgius Jago, p. 163, f. 3. 
Die Seekarausche, Lutjanus rupestris, Bloch. Naturg. der Aus- 
landischen fische, ii. p. 117, pL 250, fig. 1. 
VII. Observations on some circumstances attending the process of 
Exuviation in Shrimps and Lobsters. By JONATHAN COUCH, 
F. L. S. 
Dr MILNE-EDWARDS, in his Histoire Naturelle des Crustaces, 
has given an account of what may be considered the present state of 
our knowledge, of the circumstances under which the process of ex- 
uviation is effected, and the methods by which it is accomplished 
in the long-tailed stalk-eyed crustaceans ; but as much of what that 
eminent naturalist advances is derived from other authorities, and 
I have reason to conclude, contrary to the general opinion, that the 
circumstances attending this process of nature, are different in even 
nearly allied species, there still remains space for enquiry. 
Reaumur is our only original authority for the minute circum- 
stances attending the process of exuviation, which he observed in the 
River Crayfish (Potamobius fluviatilis, Leach ;) but not having an 
opportunity of consulting that author's work, I copy his narrative 
from Dr M. Edwards's quotation : " A few days previous to the com- 
mencement of the operation, the creature abstains from all solid 
nourishment, and the carapace and abdominal segments will be found 
to offer less than the usual resistance to the pressure of the finger. 
Shortly afterwards the crayfish appears restless, and rubs its legs 
against each other ; it then throws itself on its back, agitates its 
whole body and then distends it, by which the membrane joining 
