10 January 2006

Prospecting for snails on a cold afternoon

While taking a walk on a cold and windy afternoon last weekend, I spotted a couple of things―I believe they are called pallets―discarded on a wooded slope. Pallets are wooden frames about 1 m x 1 m that are used as shipping crates. From the condition they were in it looked like they had been there for several years. Whenever I come upon something wide and flat in the woods (and anywhere else) I can’t resist the urge to lift it up and look under it. The picture on the left shows one of the raised pallets supported by my tripod.

The first thing I noticed under the pallet was a large snail shell that I could identify right away as Mesodon thyroidus, a common denizen of the forests around here. Then, I found another one and another one and another one...At the end I had 9 empty adult M. thyroidus shells.

There was also a small juvenile of the same species dormant in its shell. I took the empty shells, but put the juvenile back under the pallet. I also noticed 2 clusters of slug eggs, probably those of an Arion introduced from Europe. The tulip poplar (Liriodendron tulipifera) seed at the lower left corner provides a scale.

Next I looked under the other pallet, which was about 10 m away. There I found 2 more empty M. thyroidus and 2 empty shells of the larger Neohelix albolabris.

These snails seem to like to take refuge under these pallets. The moral of today’s tale is that trash left where it shouldn’t have been left isn’t always bad.


MattK said...

I have noticed that you have several posts about Mesodon and Neohelix and I was wondering if you could tell me how to distinguish these genera. Any help would be appreciated.




Around here there are only Neohelix albolabris & Mesodon thyroidus. They are easy to tell apart, because Neohelix is usually larger & has a completely closed umbilicus, whereas Mesodon has a partially closed umbilicus. Most shells of the latter also have a parietal tooth.

There are also anatomical differences between the 2.

I don't have time to look up the defining differences between the 2 genera.

Matt said...

Thanks for the help. I am trying to catalog specimens from the collection of the late malacologist F. Wayne Grimm. Unfortunately, I myself am not a malacologist. However, I am trying to learn to make at least some determinations for undetermined specimens, at least to the level of family or genus, as I go along. That will hopefully save some work down the road and will allow some specimens to be flagged for further work. I am not limited to only two species. Some of the specimens determined to be Mesodon were completely imperforate. In any case, I am not able to perform dissections since it is outside of the scope of my current tasks.