These three drawings, all from one album, may be compared to 71 drawings of tulips and shells by the same hand in an album in the Fondation Custodia, Institut Néerlandais, Paris, which bears an inscription 'B. van der Ast'. These drawings are generally attributed to Assteyn. A comparable drawing of a tulip from the Van Leeuwen Collection is offered in these Rooms, 24 November 1992, lot 8.
M.D. Haga has kindly identified the shells as respectively a Comus, a Turbo pica and a Panthershell