THE NAME ASTACUS FLUVIATILIS. 289 



island, has or has not been effected by artificial means, is 

 involved in some obscurity. 



English zoologists have always termed our crayfish 

 Astacus fliiviatilis ; and, up to a recent period, the 

 majority of Continental naturalists have included a 

 corresponding form of Astacus under that specific name. 



Thus M. Milne Edwards, in his classical work on the 

 Crustacea* published in 1837, observes under the head of 

 "Ecrevisse commune. Astacus fluviatilis :^' " There are 

 two varieties of this crayfish ; in the one, the rostrum 

 graduall}^ becomes narrower from its base onwards, and 

 the lateral spines are situated close to its extremity; 

 in the other, the lateral edges of the rostrum are parallel 

 in their posterior half and the lateral spines are stronger 

 and more remote from the end." 



The " first variety," here mentioned, is known under 

 the name of " Ecrevisse a pieds blancs " f in France, 

 by way of distinction from the " second variety," which 

 is termed "Ecrevisse a pieds rouges," on account of 

 the more or less extensive red coloration of the forceps 

 and ambulatory limbs. This second variety is the larger, 

 commonly attaining five inches in length, and sometimes 

 reaching much larger dimensions ; and it is more highly 

 esteemed for the market, on account of its better flavour. 

 In Germany, the two forms have long been popularly 

 distinguished, the former by the name of " Steinkrebs," 



* " Histoire Naturelle des Crustacea." 

 f Carbonnier. ' ' L'Ecrevisse, " p. 8. 



