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 fluviatilis; 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 
“Kerevisse commune. Astacus fluviatilis :” “There are 
two varieties of this crayfish; in the one, the rostrum 
gradually 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 “Kerevisse a pieds blancs” + 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 Crustacés.” 
 Carbonnier, ‘‘LEcrevisse,” p. 8. 
