The normal English pronunciation of Cepaea, believe it or not, would be /səˈpiː(j)ə/. Some speakers would use an /aɪ/ dipthong there for ae instead of /iː/
English pronunciation of Latin (and Greek) has an extremely long and complex history. So words like Linum (the genus of the common flax plant) end up coming out as /ˈlaɪnəm/ not as /ˈlinum/. Yes, I know this is strange, but if you don't do it this way, it messes up our poetry, where this pronunciation is expected.
You can, and probably should, read the Wikipedia article on the Traditional English pronunciation of Latin.
That means that Caesar is /ˈsiːzəɹ/ not /ˈkaɪsaɾ/, while things like Menelaus come out as /ˌmɛnɪˈleɪəs/. Strange but true.