dwkfoster's Identifications

Razor-shells need careful consideration when attempting identification. The key areas are highlighted in Picture 1
The Pallial Line is the most useful field-feature and one should angle the specimen, so that the light may reflect from these lines. They are not always easy to see nor photograph..
The Hinge Teeth are usually visible but require more detailed knowledge or a text key to hand,
The Atlantic Jackknife
Ensis leei (see Comments) has a unique Pallial Sinus and teeth arrangement. It is commonly found in Europe and can be mistaken for Ensis ensis https://www.gbif.org/species/8485639