32 



PAL^ONTOLOOY OF NEW-YORK. 



The preservation of these trails in arenaceous and semi-arenaceous deposits of the Clinton 

 group, in such condition that we recognize them at once, deciding without hesitation as to their 

 general character and origin, suggests a question, whether similar markings, preserved under 

 other circumstances, and where the primitive character of the deposit has been metamorphosed 

 or obscured from other causes, may not have been differently interpreted. The fimbriated tracks 

 on Plate xiii are not very different in their general character from the JVereites ; and this similar- 

 ity very forcibly impressed me on their first discovery, in the specimen fig. 2, pi. 13. If we 

 compare, for example, the JVcreites loomisi of Emmons {Taconic System in -^gr. Report, Vol. 

 i, pi. 15), there is not a great dissimilarity between it and the fig. 1 a, pi. 13 of this volume. 

 Compare also J^ereites gracilis, Ejimons, Plate xvi, fig. 3, with fig. 2, pi. 13 of this volume. 

 Going still farther in the figures 16, 1 c. Id, and fig. 2, and in>.iuding those on Plate xiv, 

 we shall be ready to conclude that these individual specimens, under other circumstances, 

 might have been mistaken for species of JVereites. Again the Myrianites, JVemerites, &c. find 

 not very dissimilar representations in the smooth trails on Plates xi and xii. It should be 

 observed, also, that these specimens of trails form but an imperfect exhibition of the great 

 number and variety of character which may be obtained at the localities named. 



I have not, it is true, had an opportunity of examining the specimens from which the original 

 species of these genera were described by Mr. Muhcuison ; but those from which Professor 

 Emmons has described species are, many of them, not very unlike the trails of some marine 

 animal upon the surface*. It is true that in the metamorphosis which the slaty rocks of Maine 

 have undergone, it may not be easy to decide that such markings have been originally trails 

 upon the surface preserved by subsequent depositions. 



In comparing the actual specimens of JVereites, Myrianites, &c. from the State of Maine, 

 with the specimens from the Clinton group, there is a great similarity in general character, 

 though not in the material of the rock. There are also upon the Maine specimens markings 

 very similar to those on Plates xi and xii of this volume, which show no evidence of fimbrise 

 or other appendages like the JVereites. Many of the JVereites also have not the regular coiled 

 or folded character of most of the specimens figured, but are seen meandering over a consider- 

 able extent of surface. Upon the same slabs, too, may be seen those of various character and 

 different species crossing each other. On the one side these markings present a continuous 

 groove or channel with the fimbria attached ; and on the opposite side, or portion separated, a 

 continuous elevation corresponding to the groove, and neither presenting any evidence of ar- 

 ticulations. Moreover there is not, in any of the specimens examined, any apparent remains of 

 organic structure ; not even a film of matter differing from the surrounding rock, or a dis- 

 coloration of the surfacef . 



* Aa a fact in proof of tVie similarity of the trails of other animals to these supposed remains of Annelida, I may 

 mention that the .Vemapodia tenuissima of Emmons has been proved to be the trail of some existing animal OTer 

 the outer surface of the rock, removing the minute lichen which covers it, and discoloring the rock beneath. 



t For further details and llhistrationH, see note at the end of this vnlume. 



