Insects. 5533 



during the latter part of winter, the back was covered with minute corallines and 

 Serpulae ; but during the summer, and during the migratory season, the shell is smooth 

 and clean. The general colour is a light fawn flesh-colour, inclining occasionally to 

 a brown, and in some specimens to a black-brown colour. Several of the specimens 

 while under examination passed through the process of casting their shells, and this 

 was attentively watched: the general mode in which it is effected is precisely the same 

 as in Carcinas Maenas. When the process has begun, the crab retires to the shelter 

 of some overhanging rock or imbeds itself in the sand, and becomes entirely helpless ; 

 the posterior margin of the carapace gets lifted, and a soft substance protrudes through 

 the opening : this increases, and the carapace gels more and more elevated, the 

 waved margin or suture in front gets loose, and the body is drawn gradually out. 

 Several of these perfected the exuviation in my hand, and, on immediate careful 

 examination of the claws, I found that Reaumur is quite correct in saying that all the 

 claws have a longitudinal slit, to allow of the escape of the broad internal muscular 

 plates ; these semicalcareous plates have their fixed part placed distally, their proxi- 

 mate surfaces being free, and affording wide attachments to the muscles of the limbs : 

 in casting their shell these are left behind, which is done by their dividing the edge 

 of each claw longitudinally : this is not only the case in the present species, but also 

 in the Maia, in which it has been said not to occur. Immediately they escape from 

 the shell, I have been enabled to separate the edges with a pin on all occasions; but 

 in the course of ten minutes the surfaces become so intimately united as to present no 

 traces of such a fact, — no line, no furrow, nor even a shade whereby the situation of 

 the fissure could be detected, — the shell is entire in all its parts. From Mr. Gosse's 

 remarks, that " neither were the shells split to afford a lateral passage for the limbs," 

 &c, I suspect he has mistaken Reaumur's remarks. The shells are split in no part, 

 but the soft claws of the escaping animal are, as, from the circumstances of the case 

 they must be, for how else could such broad disks be drawn from the inside of a claw? 

 In examining the large kind of Crustacea in various stages of preparation for the 

 moult, I find that these large muscular disks undergo a change on both surfaces : the 

 muscular masses are less firmly attached, and this becomes so apparent, that, besides 

 becoming more fluid, they are found to be attached to a stout membrane, between 

 which the solid plates lie, and from which in exuviation they are drawn out: these two 

 membranes finally fall together and form the new plate, by subsequent consolidation. 

 — R. Q. Couch ; Penzance. 



An Appeal to British Entomologists. — Brother entomologists ! The study of 

 Entomology may be said to promote four results: 1st. It is calculated to attract and 

 please the eye— I mean the making a collection. This is the lowest result: in saying 

 this, I am far from insinuating that it is an unworthy result: as well might we object 

 to a traveller experiencing feelings of delight and gratification while he beholds some 

 glorious panorama of nature. If therefore there be no other aim in view in making a 

 collection than the mere pleasure of looking at and examining it, I consider such 

 object highly praiseworthy and commendable. 2ndly. It is calculated to further 

 Science, and, more or less directly, to promote the welfare of mankind, as has been 

 admirably shown in the * Introduction to Entomology.' 3rdly. It is calculated to 

 elevate the moral tone, by supplying occupation to the idle, and by affording to the 



