chap, xxi.] SECONDARY SYMMETRY : CRUSTACEA. 



527 



each bearing a complete leg. When seen by me the leg marked L' 

 was lost. 



Normal left 1 



Fig. 180. Palinurus vulgaris, No. 808. Left penultim ate walking leg. (After 

 Leger. ) 



I could not quite satisfy myself as to which of the three was 

 the normal, but it was clear that R' was in form a right leg and 

 that the other two were lefts. If the leg L' is the normal, it 

 has been pushed out of place by a pair of extra legs in Posi- 

 tion DAA, but if R' and L' be the extra legs, then the most 

 anterior leg is the normal and has been pushed out of place by a 

 pair in Position VPP. For an opportunity of examining this 

 specimen, I am obliged to the courtesy of Prof. A. Milne Edwards. 

 Originally described and figured by Leger, M., Ann. Sci. Nat., 

 ZooL, 1886, S. vii. I, p. Ill, PL 6. 



809. Lithodes arctica : 2nd leg on right side has terminal joint as 

 shewn in Fig. 181, II. If R be the normal then R' and L' are a pair in 

 Position V, but if R' be the normal then R and L' are a pair in Position 

 D. Attention called to the great diminution in size of all three termi- 

 nations as compared with the normal (Fig. 181, I). Original description, 

 Herklots, J. A., Bijdr. tot d. h. Genootsch. Nat. Artis Mag., 1852, iv. 

 p. 37, PI. ; repeated Arch, neerl., 1870, v. p. 410, PI. XI. 



810. Cancer pagurus : last left leg closely like last case [in Position 

 D]. Richard, Arch. Zool. exp., 1893, p. 102, _/?'#-. 



811. Carcinus maenas : 2nd amb. leg as in Fig. 181, III. A pair of 



