This section is from the book "Soyer's Standard Cookery", by Nicolas Soyer. Also available from Amazon: Soyer's Standard Cookery.
Cook the crayfish with two tablespoonfuls of mirepoix. Finely pound the shells after having removed the tails, and add thereto three ounces of butter per two ounces; rub through a fine sieve and add a little cochineal.
The whole crayfish may be pounded, but the tails are usually laid aside with a view to supplying the garnish of the toasts for which the butter is intended.
Pound very finely, the remains and shells of crayfish cooked in Mirepoix. Add their weight of butter, and strain through a fine sieve, to remove any shell particles.
 
Continue to: