THE NAUTILUS. 35- 



The skulls of tlie mastodon were found partly in and partly under 

 the semi-ligneous peat, showing the shells to be as old or older than 

 the mastodon. You may think, What has all this to do with shells? 

 It is to give you, dear reader, some small idea of how long these shells 

 have been lying there in what was once thought to be their last 

 resting place, and how little the species differ from the same kind of 

 the present day. The shells, so far as found, are as follows : 



LimncEa stagnalis L., L. desidiosa Say, L. hunrilis Say ; Planorbis 

 dfflectus Say, P. parvus Say, P. bicarinatus Say, P. trivolvis Say, 

 P. campanulatus Say; Ancyhis riviilaris Say; Amnicola limoxa .Say, 

 A. histrica Pils.; Campeloma integer Say, (1 obesum Lewis, ('. sub- 

 solidtnn Anth.; P/n/sa ancillaria Say, P. heterostropha Say, P. in- 

 tegra Hald.; StroMlops labyrinthica Say; Succinea ova/is Gld.; Cary- 

 cliium exiginuu Say; Valvata tricarinata Say; Zonites radiatulus Aid.; 

 Pleurocera clevalum Say, Goniobasis livescens Mke., Margaritana 

 rtigosa Bar., M. deltoidea Lea, Anodonta subcylindracea Lea, A. 

 Jootiana Lea, Sphcerium simile Say, S. striatinnm Lam., Pfsidium 

 compressinn Prime, Unio pressus Lea, U. novi-eboraci Lea, U. ven- 

 tricos/fs Bar., U. spatulatus Lea. 



All the shells are white and very frail except the Pleurocera ele- 

 va/1/in, which is strong and still retains its coloring. The Limntza 

 stayiiah's is larger than any that has come to my notice of the present 

 day shells, some of them measuring over two inches long, and the 

 Pluiiorbis campanulatus and bicarinatus are also very large, larger 

 than the present day shells of the same species. The Valvata tri- 

 carinata was also larger than any that 1 have seen and was quite 

 plentiful. 



One thing struck me as rather singular, that the shells seemed to 

 be in colonies. For instance, take the whole line of that ditch, and 

 there was only one place about a rod long where the Pleurocera ele- 

 vatinn was found, and the other shells had their localities where they 

 were plentiful and almost none at all elsewhere. The Valvata tri- 

 carinata seemed to be as evenly distributed as any, and it was more 

 plentiful in some places than it was in others. 



There are many things to be found by a, careful observer in over- 

 hauling a mass of such stuff as that lake drift. For instance, Prof. 

 Cram in searching a lump of the dirt found a perfect skeleton head 

 of a fly of the general appearance of our house fly, oniy larger, and 

 we found unmistakable evidence of man by the presence of flint im- 

 plements and horn tools. 



