338 WALCOTT 



Matthew) is 3000 feet below the horizon of the Upper Cam- 

 brian fauna and 1450 feet above the horizon of the Olenellus 

 gtlbertt fauna. 



{d) That in the southern Appalachians the Olenellus fauna 

 occurs more than 7000 feet below the highest Cambrian fauna 

 known in that region, and fully 2000 feet below a typical Ole- 

 noides fauna. 



To the geologist the position of the Olenellus fauna is well 

 assured. Theoretic biology may question the facts of strat- 

 igraphy, but, as many paleontologists have learned in the past, it 

 is dangerous to base broad generalizations on the relatively small 

 amount of biologic data available from the older Paleozoic strata. 



It may not be out of place to call attention to the range of the 

 Olenellus fauna at the locality where the types of the genus 

 were first found, at Parker's quarry, township of Georgia, Ver- 

 mont. The base of the section is at the western face of the 

 cliff overlooking the level that reaches to the shore of Lake 

 Champlain. Here the massive magnesian limestones have a 

 low dip to the southeast. The section continues without a 

 stratigraphic break to the Georgia shales at Parker's quarry, 

 where O. thompsont occurs in association with O. {Mesonacts) 

 vermontana. At a point 970 feet below this horizon I found, in 

 1895, heads of a species of Olenellus associated with Oholella 

 crassa. From the fact that Olenellus (?) asapkoides is asso- 

 ciated with the latter at Troy, N. Y., it may be that the heads 

 found represent that species. In any event this section clearly 

 proves that representatives of Olenellus have a range of over 

 a thousand feet at the typical locality of the genus in Vermont.^ 



Nomenclature. 



Mr. Matthew proposed the term ' Etcheminian ' for a pre- 

 Cambrian Paleozoic terrane which I think has been shown to be 

 equivalent to the Lower Cambrian terrane of the classification 

 established in 1888 for which the term Georgian was adopted. 

 The term ' Etcheminian ' was proposed for a distinct system of 

 rocks corresponding in classification to the order of Cambrian, 



ipor a detailed description of this section see Bull. U. S. Geol. Survey, No. 

 81, pp. 278, 279. 



