1890.] REPETITION OF PARTS IN ANIMALS. 583 



Though there is not sufficient evidence for determining the ques- 

 tion, it ma^' be mentioned that the general appearance suggests that 

 the double dactylopodite, D, is the normal one of the limb and 

 that the process, P, which is warped over to meet it, is the process 

 normally opposed to it. The process P', which is opposed to the 

 dactylopodite, D', is comparatively small and ill-developed. 



The class of variation shown by these three specimens is not un- 

 common amongst Decapoda {cf. Paxon, Leger, &c.). 



In addition to these cases an especially interesting one shovdd be 

 mentioned which was communicated to me by Mr. G. C. .Bourne, 

 Director of the Marine Biological Laboratory. This specimen, which 

 was not seen by myself, was sent to Mr. Bourne by Mr. Dunn of 

 Mevagissey, Cornwall. It was an edible Crab (C. pcic/itrus), 

 measuring about 2"o inches across. In this specimen the three 

 posterior walking-legs of one side were seen to be each repeated. It 

 had lately moulted and was much decomposed when received. Un- 

 fortunately an imperfect examination of it was made and the speci- 

 men has been destroyed. Similar occurrences among Crustacea and 

 insects have been recorded by Leger and others. 



III. — Beetle (Chrysomela banksii) having three complete 

 Tarsi on one Leg. 



This specimen was kindly lent to me for description by Dr. Sharp, 

 who obtained it from the 2^ew Porest. 



It was exhibited at a meeting of the Entomological Society in 

 1862, but has not been figured or described in detail. The tibia 

 of the third leg on the right side has the form shown in the figure, 



A, Abnormal right posterior leg of Chrysomela banksii. B, Normal leg in the 

 Bome position, from a rather larger specimen (enlarged to scale). 



(Figures drawn by Mr. Edwin Wilson.) 



Its outer extremity, which is widened into a flat, club-shaped 

 structure, bears three complete tarsi, each of which is perfect in all 

 its four joints and carries a pair of normal claws. These three tarsi 

 are equal in size, but are very slightly smaller than those of the same 

 leg on the other side. 



In addition to the three tarsi the tibia is produced into a small 

 horn, which projects from it rigidly, having no articulation. At the 



