This section is from the book "The Steward's Handbook And Guide To Party Catering", by Jessup Whitehead. Also available from Amazon: Larousse Gastronomique.
"I wonder when the moderr caterer and book-writer, as well as the fishmonger, who ought to know better, will cease to stumble between the Scylla and Charybdis of cray and craw lish. The former is a small crustacean found in the mouths of rivers, and the other, as a rule, larger lhan a lobster and a sea and harbor fish. The meat of both is rich in inozilc, animal sugar, which easily distinguishes it from that of the lobster. Again, the crawfish is sweeter than the crayfish. The identical crawfish for this dinner were sold as crayfish; and I remember in 1SS0 having to review a cook book, from the pen of an illustrious writer, where the two were confounded, and the man posed as a naturalist, too".
Roast crawfish; the fish marinaded in vinegar and oil, or brushed over with vinegar several times, then with butter and roasted in a very hot oven with frequent basting. When the shell becomes soft it is done; white sauce with wine, lemon juice, mace, etc.