182 



Scientific Geology. 



very much resembling those above described. And I find that they 

 effervesce with acids, which proves their identity. Some of them so 

 exactly resemble Unios in form, that I at first suspected them to be 

 petrifactions. But a careful examination satisfies me that the simi- 

 larity is accidental. This fact shows us that the same causes operated 

 when this sandstone (a variety of the new red sandstone) was depos- 

 ited, as when the newest tertiary was formed. A fact analogous to 

 the one just stated is mentioned by Dr/Macculloch. " In the argilla- 

 ceous limestones, as well as in the accompanying sandstones," says 

 he, " highly flattened spheroids of large dimensions are found at- 

 tached in pairs by a crylindrical stem, and imbedded in the surround- 

 ing rock."* 



Organic Remains. 



The newest tertiary in Massachusetts, judging from the examina- 

 tions which I have made of it, is remarkably wanting in organic re- 

 mains. Indeed, I have found but a single genus, and even this is in 

 so imperfect a state that I have been unable to ascertain its nature. 

 It was probably some kind of animal : and some of the specimens 

 bear a considerable resemblance to the Ovulites margantula of Gold- 

 fuss' Petrifacta: but I have never seen in it any thing of the "poris 

 minutissimis ad superficiem amussim dispositis," which he represents 

 as belonging to that petrifaction. Other specimens resemble the 

 Scyphia of the same author, but the " e fibris reticularis " is wanting. 

 It is doubtful whether the sketches which I have given of this relic, 

 (Plate XI. Figs. 18, 19, 20, and 21,) represent anything more than 

 fragments of it, worn into an ovoid shape. Fig. 22, however, does 

 certainly represent one extremity of the animal unaltered : for it is 

 still partly enveloped in loam. But the fragments are sometimes 

 cylindrical, varying in size from a quarter of an inch to more than 

 an inch in diameter. These usually perforate the strata of clay per- 

 pendicularly ; that is, at right angles to the layers ; and they are 

 sometimes several inches long. The extremities, however, I appre- 

 hend are always similar to Fig. 22. The most decisive evidence of 

 organic structure which these remains exhibit, is a longitudinal per- 

 foration of the size of a knitting needle. They are, it is true, easily 

 divisible transversely : but this seems to depend upon the laminated 

 structure of the clay, that chiefly composes them, and not upon the 



* System of Geology, Vol. 1. p. 179. 



