BUFFALO SOCIETY OF NATURAL SCIENCES 197 



this reason it is impossible from a study of the fauna, flora and sedi- 

 ments of that region alone to arrive at any conclusion as to the habi- 

 tat of one group of the organisms whose remains are found there. 

 If, for instance, we had no information from other sources regarding 

 the ecology of the pelecypods, it would not be safe to infer that they 

 were marine organisms because associated with brachiopods, nor 

 would it, on the other hand, be fair to assume that they were terres- 

 trial because ferns were embedded in the same strata. The same 

 may be said for the eurypterids; nothing regarding their habitat can 

 be inferred from their appearance in such beds as these sandstones 

 with a commingled marine and terrestrial assemblage of organic 

 remains. In some cases it is possible to take account of more factors, 

 such as the relative perfection of preservation of the various groups of 

 organisms when one, perhaps, shows evidences of transporation and 

 consequent maceration, or again, the relative scarcity or abundance 

 of species and individuals. In the instance of the sandstones of 

 Condroz, I think that it is justifiable to attach importance to the 

 sparse and fragmentary condition of the eurypterids as compared with 

 the abundance and good condition of the other organic remains, and 

 to conclude that probably the merostomes did not live in the region 

 where their fragments finally came to rest. 



2. The truth of the thesis of the above paragraphs being accepted, 

 it must be acknowledged a fortiori that a single fragment or even a 

 complete individual in a stratum in which occur no remains of typical 

 marine organisms, intercalated in strata which do, is not the slightest 

 proof that the eurypterid was an inhabitant of the sea. 



I may here, as an illustration, give an account of the occurrence 

 of Strabops thacheri, the only known eurypterid from the Upper 

 Cambric or Lower Ordovicic Potosi Limestone of Missouri. In the 

 section near Flat River, St. Frangois Co., Missouri, given by Nason, 

 the Potosi formation is represented as. resting disconformably upon 

 the Bonne Terre or St. Joseph limestone of uncertain Cambric age, 

 but probably at least Middle if not Upper Cambric. At the base of 

 the Potosi is an edgewise conglomerate extending upward for about 

 6| feet and followed by 100 feet of conglomerates and interbedded 

 slates, the latter carrying several species of trilobites, brachiopods 

 and an occasional Hyolithes primordialis . As was stated on p. 13, 

 Beecher, who identified the fossils collected by Nason and who 

 described the one eurypterid found, did not and perhaps could not 

 state in just which layer Strabops occurred and whether it was found 



