NOTES. 



349 



According to Dulk ( "Chemisclie Untersuchung der Krebsteine:" MuUor's 

 Archiv. 1835), the gastroliths have the following composition :— 

 Animal matter soluble in water .... 

 Animal matter insoluble in water (probably cliitin) 



Phosphate of lime 



Carbonate of lime ....... 



Soda reckoned as carbonate 



The proportion of mineral to animal matter and of phosphate to car- 

 boTiate of lime is therefore greater in the gastroliths than in the exo- 

 Bkeleton in general. 



Note III., Chapter I., p. 31. 

 GROWTH OF CRAYFISH. 



The statements in the text, after the words » By the end of the year," 

 regarding the sizes of the crayfish at different ages, are given on the 

 authority of M. Carbonnier (L'Ecrevisse. Paris, 18C9) ; but they obviously 

 apply only to the large "Ecrevisse k pieds rouges" of France, and not to 

 the English crayfish, which appears to be identical with the " Ecrevisse 

 a pieds blancs," and is of much smaller size. According to M. Carbonnier 

 (1. c. p. 51), the young crayfish just born is " un centimetre et demi 

 environ," that is to say, three-fifths of an inch long. The young of the 

 English crayfish still attached to the mother, which I have seen, rarely 

 exceeds half this length. 



M. Soubeiran (" Sur I'histoire naturelle et I'education des lEcrevisses :" 

 Comptes Rendus, LX. 18G5) gives the result of his study of the growth 

 of the crayfishes reared at Claii'efontaine, near Rambouillet, in the 

 following table : 



These observations must also apply to the " Ecrevisse a pieds rouges." 



