INTRODUCTORY REMARKS. 5 



tcrs can be made out from the imperfect specimens) to Upper 8iluiian as 

 lo Devonian types. Tlie Spirifer, liowever, is ver>/ closely allied to forms 

 found in the Upper Helderberg (Devonian) limestones, at the Falls of the 

 (Jhio; while the specimens of Atnjpa reticularis belong to a varietv very 

 common in rocks of that age in the vicinity of Louisville, Kv., and in the 

 neighboring portions of Indiana. It is also worthy of note, that these fossils 

 were found quite abundant, weathered out of the mati-ix, and that they are 

 silicified and in all respects similar, in their state of preservation, to the 

 Upper Ilelderberg fossils, so common in- the Western States mentioned 

 above. From these facts, it is highly probable that these Pinon Ivange fos- 

 sils came from a rock belonging to about that horizon. 



The other Devonian fossils, figured on plates 2 and 3, came from an 

 entirely distinct rock from those mentioned above, and are more than usually 

 interesting, because they were found, with a few excejitions, in the formation 

 containing the rich silver-mines of the White Pine Mining District, Nevada, 

 lliey were all found in a dark-colored or grayish matrix, entirely different 

 from that containing the Pinon Station fossils mentioned above. Those from 

 the AVhite Pine District consist of several species of Corals, l>racliio]»ods, and 

 two species of OrtJiocerns. Among the Corals, there are species that seem to 

 bo undistinguishable from the European Devonian forms Acervularia penta- 

 gona and Smithia Hciinahii. The other Corals are an apparentl)^ new AJre- 

 olites and a DiphjphuUuin* The Brachiopods consist of a small I'rodi(ctiis, 

 at least allied to the Devonian species P. subacuJeatus, Atnjpa reticularis, a 

 small Hemipronites, apparently undistinguishable from a New York Hamil- 

 ton Group species, and several small Spirifers, some of which resemble Ilam- 

 ilt(^n Group forms. 



The presence of the genera Productus and Smithia ^^'oulll alone l)e a 

 strong argument, in the present state of paheontological science, against the 

 supposition that these silver-bearing beds might belong to the Silurian, to 

 say nothing of the specific affinities of these and the associated fossils; while 

 the occurrence in the same beds of Atrypa reticularis, and the Acervularia, 

 Smithia, and Ptychophyllum, with the specific affinities of the other fossils, 



* The little Fai-ositcs aud Cyathophylhm, represented by figures 2 aud 3 of pinto 

 2, are from a different horizon in Arizona. 



