Here's an 18th-century Irish clam soup recipe, keep meaning to try it but haven't yet (clams are dear here):

Clam Soup, (Prepared By A Dublin Lady.)
Put forty or fifty clams, in the shells, with as little water as possible. When the liquor has run out from the opened shells, take the clams out and chop them fine, with an onion, a bunch of minced celery, and some mace and pepper. Put all in the soup, and thicken it with two tablespoonfuls of butter rolled in flour, and if you choose, add a little milk. Simmer twenty minutes; stir in the beaten yolks of five eggs; put bits of toasted bread into the tureen and serve.
(From The New Cyclopaedia of Domestic Economy, and Practical Housekeeper by Elizabeth Fries Ellet, Publisher Henry Bill, 1872)