THE 



QUARTERLY JOURNAL 



October, 1825. 



Art. I.— On the Means by which Crabs throw off their 

 Claws. By Dr. Mac Culloch. 



[In a Letter to the Editor.] 

 Sir, 



It is well known that the tribe of crabs, using this popular 

 term to comprise many genera of modern naturalists, have the 

 power of parting with their claws by a voluntary effort ; and they 

 are thus frequently taken, with one or more of these deficient, or 

 of an inferior size to the rest, since they have also the power of re- 

 producing them. As the nature of this singular process has never 

 been described, and as it appears, at first sight, as it has always 

 been conceived, a very unaccountable effect of voluntary or mus- 

 cular power, I am induced to send you a sketch of the anatomy of 

 the parts engaged ; with an explanation of the mode in which the 

 animal appears to detach the limbs. 



This process appears to be effected by these animals whenever 

 so serious an injury has been committed on any of the extreme 

 phalanges as to render the claw useless ; no provision having been 

 apparently made to repair any injury of those parts, although there 

 has been one established for reproducing the whole limb. It is 

 very easy to witness this effect when the animal is recently taken 

 out of the water and in a vigorous state ; but a very short time is 

 sufficient, in most species, to render the animal too feeble to per- 



Vol. XX. B 



