PAL/EOTROCHIS 229 



chiefl}' of granular quartz, but may often contain also traces of spherulites, and a 

 few of those examined are made up wholly of fibrous feldspathic material— ?'. e., 

 they are spherulites. In those which are composed of spherulitic matter with 

 gi-anular quartz the latter sends numerous veins of granular quartz into the spher- 

 ulitic portion, as well as into the surrounding spherulites, and it is evident that the 

 granular quartz was deposited after the development of the spherulites. Recogniz- 

 ing this Palfeotrochis rock as a more or less altered ancient volcanic (according to 

 Holmes, preCambrian) fall of spherulites, it is easy to understand the great varia- 

 tion in the form, size, and composition of the nodules. 



"The Paleeotrochis rock is evidently closely related to the acid volcanics studied 

 by Wadsworth* and others in the vicinity of Boston and those of the South 

 mountain, in Pennsylvania and Maryland, described by Dr G. H. Williams f and 

 Miss Bascom.J 



"About a year ago biconical forms like Palteotrochis were presented by Mr Tadat- 

 sugu Kochibi, Director of the Geological Survey of Japan, to the United States Geo- 

 logical Survey. These specimens are now in the National Museum, and are much 

 more regular in form, size, and general appearance than the Palfeotrochis of North 

 Carolina. They are of a pale pink color, with regular biconical, striated forms, and 

 in some cases have shallow pits in one of the apices. They are known in Japan as 

 ' Soroban ishi,' or abacus stones. One of these specimens contains a small fragment 

 of the rock from which these curious specimens were obtained, and it appears to be 

 spherulitic. According to Mr Willis, who obtained the information directly from 

 Mr Kochibi, ' these stones are found only in rhyolitic tuffs. They not infrequently 

 occur much larger than these specimens, possibly up to two inches in diameter or 

 more, and are more frequently associated in groups of two or three overlapping or 

 coalescing. They are generally white, the rosy tint of these specimens being a 

 rare characteristic' A thin-section of one of these ' abacus stones' shows it to be 

 an agate of which the outer layers are pink and the inner white. There can be 

 no doubt in this case that the form resulted from the filling of the cavity long after 

 the solidification of the igneous material." 



LAKE SUPERIOR SERIES 



Fossils have been reported from time to time from the lake Superior 

 pre-Cambrian rocks, but there does not yet appear to be any i^ositive 

 evidence that they have been found in the Keweenaw, the Huronian, or 

 in any of the formations that may be referred to the Algonkian. 



In a paper by W. S. Gresley § fossils are described which were found 

 by him in heaps of iron ores upon the docks at Erie, Pennsylvania. The 

 locality was identified on the statement of the dock superintendent that 

 the majority of the specimens came from the Chapin mine, Iron mountain, 

 Menominee range, Michigan. 



Professor C. R. Van Hise informs me that in the Menominee district 

 at various points ore is mined from the basal Cambrian, the ore being 



*Bull. of the Museum of Comparative Zoology, Harvard College, vol. v, p. 282, and vol. vii, p. 165. 

 t Journal of Geology, vol. ii, p. 1, 1894. 

 X Bull. U. S. Geol. Survey, no. 136. 



g Traces of organic remains from the Huronian (?) series at Iron Mountain, Michigan, etc. Trans. 

 Min. Inst. Min. Engineers, 1896, vol. xxvi, p. 527. 



