1889-90.1 PELOTECHTHEN BALANOIDES. 213 



PELOTECHTHEN BALANOIDES. 



By Arthur Harvey, Esq. 



(Read 2nd November, iS8g.) 



In the paper on " Broad Outlines of the Geoloc^y of the North of Lake 

 Superior," which I had the pleasure of reading to the Institute last session, 

 I animadverted on the lack of fossils in the archa^an rocks. Yet the term 

 Azoic, as an equivalent to Archaean, has always seemed to me too hope- 

 less, and I made a very close examination, during the past summer, of 

 the Animikie formations (Hunt) in the mining district west of Port 

 Arthur, for the purpose of finding traces of life. 



There are few things in geology more confused than the nomenclature 

 of these ancient rocks. The name Huronian was proposed by Sir Wm. 

 Logan, long ago, for a series later than the Laurentian, which attains dis- 

 tinctive development to the north of the Great Lake of the Huron Indians. 

 The mind gets bewildered with the recent Huronian sub-divisions, such as 

 "Taconic" (Emmons), "Animikie" (Hunt), "Keewatin" (Lawson), " Kee- 

 weenaw" (Irving), and I think they ought all to be consigned to oblivion 

 at once — as they will be in the end. The district I examined rests on a red 

 Huronian granite, on which is a green (chloritic) slate, over which is a 

 great thickness of black slate (argillite) with layers of chert or silicious 

 limestone near the junctions ; the whole capped in many places by what 

 is locally called trap — a greenstone or gabbro, an eruptive overflow. 



Specimens of these rocks are in our museum, and among those pre- 

 sented by myself are some of what our Geological Survey calls " con- 

 cretionary masses." Possibly, these are alluded to in the Sixteenth 

 Annual Report of the Geol. and Nat. Hist. Survey of Minnesota, p. 317, 

 where, reading of an " argil lo-felsitic ground mass" near Ogiskie, Muncie 

 Lake, we learn that "the surface of the rock is studded with spheroidal con- 

 cretions, which have been cut in section, and have hollow centres, appa- 

 rently by the solution of the interior portion. They are not pebbles, for 

 they are all very similar, and, besides, reveal, in some cases, concentric 

 lines." In Mr. A. Winchell's report, same volume, p. 239, I find that he 

 describes, on Gunflint Lake, what he had seen elsewhere in the Animikie 

 slate — " surfaces of lamincs covered by concave depressions of an ovoid 

 or spherical character, resembling what the elder Hitchcock named Batra- 

 choides nidificans. I have discovered that spheroidal concretions between 



