542 



MERISTIC VARIATION. 



[part I. 



JC 



Fig. 200, I. Homarus americanus, right chela, No. 833. (After Faxon.) 

 II. Lupa dicantha, left chela, No. 836. LI), LI, left dactylopodite and index. 

 x, supernumerary index. (After Lucas.) 



making angle of about 45° with each other. This angle almost 

 exactly bisected by the plane in which dactylopodite moves. 

 Bell Collection, Oxford. 



835. Maia squinado : from inner side of base of 

 index of right chela arises a second index as 

 shewn in Fig. 201. It is about half as large as 

 the supposed normal index. The latter is dis- 

 placed outwards. Dactylopodite moves in ap- 

 proximately normal plane, missing both indices 

 and falling between them. Specimen kindly lent 

 by Prof. C. Stewart. 



Fig. 201. Eight chela of Maia squinado, No. 835. 

 The following are cases very similar to Nos. 834 and 835. 



836. Lupa dicantha, left chela (Fig. 200, II). Lucas, Ann. Soc. ent. 

 France, 1844, 8. 2, n. p. 43, PI. I. fig. 1. 



837. C. pagurus, right chela, 2 cases, le S&jechal, Bull. Soc. Zool. 

 France, 1888, xin. p. 125, Jig. 2. 



838. Xantho punctulatus, left chela (Fig. 202) in which the index 

 divided at about its middle to form two similar and equally diverging 

 blunt processes. Herklots, Arch, need., 1870, v. p. 410, PI. x. 



839. Homarus americanus : right chela bearing an extra index. 

 Dactylopodite does not meet the normal index. [Very doubtful if of 

 same nature as foregoing cases.] Faxon, I.e., PI. i. fig. 14. 



The following cases are exceptional. 



840. Homarus vulgaris : right chela has coxopodite single ; but basi- 



