oysters

Shucked Atlantic and Gulf Oysters (Crassostrea virginica)

Size	Extra Large or Counts	Large or Extra Select	Medium or Select	Small or Standard	Very Small
No. in a pint	less than 20	20–26	26–38	38–63	more than 63

These are also called Blue Point, and a host of other names indicating the waters in which they grew.

Shucked Pacific Oysters (Crassostrea gigus)

Size	Large	Medium	Small	Extra Small
No. in a pint	less than 8	8–12	12–18	more than 18

Kumamoto Oysters (Crassostrea sikamea)

European or Belon Oysters (Ostrea edulis)

Resources

Allan Ovenden Collard.
The oyster and dredgers of Whitstable... published with the sanction of the Whitstable Oyster Fishery Company.
London: Joseph Collard, 1902.

John R. Philpots.
Oysters, and all about them. A complete history of the titular subject, exhaustive on all points of necessary and curious information from the earliest writers to those of the present time, with numerous additions, facts, and notes. 2 volumes.
London: John Richardson and Co., 1890-1891.