NOTES. 



349 



According to Dulk("Chemische UntersuchungderKrebsteine:" Mullcr's 

 Archiv. 1855), the gastroliths have the following composition : — 



Animal matter soluble in water . . . . 

 Animal matter insoluble in water (probably chitin) 

 Phosphate of lime ... . . . . 



Carbonate of lime 



Soda reckoned as carbonate . , , . . 



11-43 



4-33 



18-60 



63-16 



1-41 



98-93 



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

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

 skeleton in general. 



Note III., Chaptee L, 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 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 Ecrevisses:" 

 Comptes Rendus, LX. 1865) gives the result of his study of the growtli 

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

 following table : 



