What We Do Citizen Science Great Eggcase Hunt British Isles & NW Europe BLACKMOUTH CATSHARK (Galeus melastomus) Size:Maximum Eggcase Length: ~5cm (ranges from 3–7cm)Maximum Eggcase Width (with keels): ~2cmRange: This deeper water species is present in the Eastern Atlantic from Norway to Senegal, including the Mediterranean. Similar Eggcase: Similar size and shape to the Smallspotted Catshark, but it has small upper horns instead of curled tendrils. Great Eggcase Hunt Records: As they're a deeper water species, the eggcases are rarely washed ashore and recorded. Manage Cookie Preferences