MUTATIONS IN CEUSTACEA OF THE FAMILY ATYIDJ]. 785 



The Researches of Bouvier and Bordage on 

 Mutations in Crustacea of the Family Atyidae. 



By 



W. T. Caiman, D.Sc, 



of the British Museum (Natural History). 



"With 4- Text-figures. 



Some six years ago Professor E. L. Bouvier (^04/05)^ called 

 attention to the remarkable dimorphism of certain tropical 

 river-prawns of the family Atyidte, which he compared with 

 the phenomenon of mutation described by de Vries in the 

 vegetable kingdom. He pointed out that the case was espe- 

 cially noteworthy, not only because of the marked discon- 

 tinuity and constant occurrence of the variations, but also 

 because they affected characters regarded as distinctive of 

 genera; and he drew the conclusion that these genera had 

 originated by a process of mutation. M. B. Bordage has 

 recently published ('08, '09a, '09b) the results of some obser- 

 vations and experiments on the living animals which seem to 

 support BouvieT^'s views, and to indicate, at all events, a 

 promising field for further investigations. At the suggestion 

 of Sir Ray Lankester the following account has been pre- 

 pared in the hope that it may induce some naturalists, who 

 have the opportunity of studying the animals under natural 

 conditions, to give attention to the matter. 



The Atyidse (see Text-fig. 1) are a family of Decapod Crus- 

 tacea belonging to the tribe Caridea (which includes most of our 

 common prawns and shrimps), and are widely distributed in 

 fresh waiters in the warmer regions of the globe (see Ortmann 

 ' The numbers refer to the list of papers on p. 796. 



