At this time of year, there is a seemingly endless variety of mysterious eggs to be found all over the landscape. In browsing through my folders of unidentified invertebrate signs just now, I came across photos of two different types of eggs I found on the undersides of yellow water lily (Nuphar variegata) leaves in western Massachusetts on June 21, 2008. I still have no idea what they are. Any ideas?
These oval, yellow eggs were embedded in a clear, gelatinous matrix, in a mass 7 mm across.
These brown, slightly more squat ones were more densely packed and, I think, without a gelatinous matrix. The mass was 19 mm long.
Added 7/4/2013: Noah reminds me (in a comment below) that these and other photos of unidentified aquatic eggs we found while working on Tracks & Sign of Insects are collected here.