On Abnormal Limbs of Crustacea. 77 



forks have been broken at the end. The length of the longest 

 is fths. of an inch. The normal forceps remain, but they are 

 shorter, and more slender than usual. Sir John G. Dalyell 

 has figured an abnormal limb having some resemblance to 

 this, but the excrescence is in the direction of the forceps, 

 though separated from them, and has two short processes from 

 the root, which are absent here.^ (b) The other specimen is 

 interesting as an exceedingly good example either of the 

 restoration of a lost part, or of the repair of an injured claw 

 — most likely the latter, as I conclude from the appearance 

 of the chitinous layer towards the point of the jointed finger, 

 and the deeply uneven surface at the base. 



III. Nephrops NoRVEGicus.— Mr B. K Peach has kindly 

 given me an excellent example of an abnormal chela in the 

 Norway lobster, accompanied by the following note : — " The 

 specimen was obtained from the Firth of Forth by the late 

 C. W. Peach some years ago. It consists of the last two 

 joints of the large claw from the right side of a Norway 

 lobster. The abnormity consists in the portion of the 

 penultimate joint, which in ordinary specimens opposes the 

 last one, being undeveloped, while the last segment is normal, 

 so that the appearance of an ordinary monodactylous v/alking 

 limb is assumed." (See Fig. 4.) 



Questions of some interest are associated with the pheno- 

 mena of abnormity in the specimens now described. Do 

 they result from injury to the crust in the stages of its 

 compacting ? Or are they the outcome of lesions in the 

 deeper tissue ? Does the repair take place before or at and 

 dependent on exuviation ? With reference to these questions 

 I notice that while students quote Eeaumur, Milne-Edwards, 

 and Bell, the peculiarly interesting and trustworthy observa- 

 tions of Sir John G. Dalyell are seldom noticed, or when his 

 facts are noticed their source is frequently not acknowledged. 

 Sir John refers ^ to one specimen of Carcinns mcenas which 

 was defective of the right claw ; to another which had even 

 lost four limbs and half the forceps of the left claw ; and to 

 a third which had been mutilated of the right claw, three 



'' " The Powers of the Creator," vol. i. (supplemental), plate Ixx. 

 ^ Ibid., p. 163. 



