Wadsworth.] 210 [April 16, 



4 'The greater part of these Huronias, so-called, are of Niagara 

 age, but the nummulated siphuncles are more marked in the Or- 

 thoceratites of the older rocks." 



After receiving the above letter with the specimen, the exami- 

 nation of the latter convinced me that it was a lava flow simu- 

 lating an organic structure, which similitude had been increased 

 by the alteration the rocks had undergone when in situ. 



The reasons for regarding it as a portion of a lava flow were 

 presented to Professor Hyatt who at that time considered it a 

 fossil. He assented to the correctness of my views when the 

 evidence was pointed out on the form itself; and also very kindly 

 consented to write a statement for publication, giving his present 

 views both for and against its organic nature, as follows : — 



" The first impression of the rock specimen from Copper Har- 

 bor or Eagle River led me to consider it the much altered re- 

 mains of a denuded specimen of the Endoceratidse. Description 

 can convey no adequate expression of the closeness of this super- 

 ficial resemblance ; it should be figured. The aspect is that of an 

 Endoceras, the chambers of which have been completely filled 

 with the* matrix, the siphon calcified and the terminal point of a 

 sheath projecting out of the calcite. This sheath having been, as 

 is common in Endoceras, filled by the matrix, is represented at this 

 terminal point by a nib of the original red rock rising in the centre 

 of the calcite. Both the apparent chambers and the siphon have 

 been worn awa}^ or denuded and the remnant covered by the ex- 

 isting matrix. The specimen as it now stands is only partially 

 uncovered exposing part of nine chambers on the left of siphon 

 and an arc above with surface continuous to the right side. On 

 the left the outer part of three chambers is exposed. In the 

 centre of the arc above rises the projecting nib of the apparent 

 sheath and a mass of surrounding calcite. 



" On the left side one sees the nine chambers nearly as in front, 

 apparently fading into the original matrix. On the right side 

 portions of the three chambers visible from the front and two 

 more, come into view, the remaining portions corresponding to 

 those on the left being apparently broken away. On the base the 

 outlines are too faint to be distinctly traceable, but either the arc 

 differs in contour decidedly from what it is above or else it is not 

 continuous. I incline to the opinion that it differs greatly in 



