NOTES. ;^-i!> 



According to Dulk ( "Clicmiscbe Untersuchung derKrebsteine:" Mulk-r'ti 

 Ai'diiv. 1835), the gastroliths have the following composition : — 



Animal matter soluble in Avater . . . .11-43 

 Animal matter insoluble in water (probabh' chitiii) 4-33 



Phosphate of lime 18-60 



Carbonate of lime ....... 63-16 



Soda reckoned as carbonate . . . . . 1 "41 



'.r8-!13 



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

 bonate of lime is therefore greater in the gastroliths than in the ex(j- 

 skeleton in general. 



Note III., Chaptek 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, 1869) ; but they obviously 

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

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

 k yjieds blancs," and is of much smaller size. According to M. Carboimier 

 (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 Thistoire naturelle et I'education des Ecrevisses:" 

 Comptes Eendus, LX. 1865) gives the result of his study of the grovrtli 

 of the crayfishes reared at Clairefontaine, near Rambouillet, in the 

 following table : 



Tliesc observations must also apply to the ■•Ecrevisse a pieds rouges.'' 



