THE NAUTILUS. 35 



The skulls of t lie 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 hist 

 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 : 



Limneea stagnalis L., L. desidiosa Say, L. humilis Say ; Planorbis 

 dejiectns Say, P. parvus Say, P. bicarinatns Say, P. trivolvis Say, 

 P. campanulatus Say; Ancylns rivularis Say ; Amnicola limosa Say, 

 A. lustrica Pils.; Campeloma integer Say. G. obesum Lewis, G. sub- 

 solidum Antli.; Physa ancillaria Say, P. heterostropka Say, P. In- 

 tegra Hald.; Strobilops labyrinthica Say; Succinea oralis Gld.; Gary- 

 chium exiguum Say; Valoata tricarinata Say; Zonites radiatulus Aid.; 

 Pleurocera elevatum Say, Goniobasis livescens Mke., Margaritana 

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

 Jootiana Lea, Sphcerium simile Say, 8. striatinum Lam., Pisidium 

 compression Prime, Unto pressus Lea, U. novi-eboraci Lea, IT. ven- 

 tricosus Bar., U. spatulatus Lea. 



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

 vatum, which is strong and still retains its coloring. The Limneea 

 Stagnalis is larger than any that has come to my notice of the present 

 day .-hells, some of them measuring over two inches long, and the 

 Planorbis 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 colonics. For instance, take the whole line of that ditch, and 

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

 vatum 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, only larger, and 

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

 plements and horn tools. 



