Dear Sir

In your “Origin of Species” 6^th. edition, page 345 you mention a Dytiscus being caught with an Ancylus adhering to it, to day while hunting for water beetles I secured a female Dytiscus marginalis with a small bivalve that I think is Sphærium corneum very firmly attached to its leg, as if the leg had been thrust between the open valves which had then closed upon it and held it fast,¹ I thought this might be interesting, and if you would care to see the specimens should be pleased to forward them to you

Yours truly | W. D. Crick.

C Darwin Esq.