REGENERATED AND ABNORMAL APPENDAGES IN THE 

 LOBSTER. 



INTRODUCTION. 



Probably most fishermen can recall some instance of a lobster 

 with abnormal claws; specimens with claws marked by peculiar 

 spurs and split tips, or again others which may have the two great 

 chelse just alike, and very rarely even a lobster with two or more 

 extra claws and limbs. These curious abnormalities have long 

 attracted the attention of museum and curio collectors, and recently 

 they have acquired a considerable degree of interest as phases of the 

 general problem of developmental mechanics. 



A number of early writers have described deformities in various 

 crustaceans, but Faxon, in 1881, was one of the first to carefully 

 review the subject and give a detailed description of deformities, 

 especially of those found in the lobster. Bateson, in his masterly 

 work on " Materials for the Study of Variation Treated with Especial 

 Regard to Discontinuity in the Origin of Species," brought together 

 all the authentic cases of abnormal structures known at his time, not 

 only in crustaceans, but in the whole animal kingdom, classified 

 them, and endeavored to determine the laws to which such varia- 

 tions might conform. Herrick ('95), in his study of the '' American 

 Lobster," devotes a chapter to "Variations in Structure," which 

 adds materially to Bateson's data. More recently, contributions 

 have been made by Andrews ('04), who describes "An Aberrant 

 Limb in the Crayfish;" Zeleny ('05 a) records the "Regeneration of 

 a Double Chelse in the Fiddler Crab;" and Przibram ('05) has made 

 an exhaustive study of the symmetry and asymmetry of limbs in 

 his monograph on " Die Heterochelie bei Decapoden Crustacun." 



