496 II. S. WILLIAMS — THE CUBOIDES ZONE AND ITS FAUNA. 



They arc particularly characteristic of higher zone?, and are abundant in 

 various Carboniferous limestones. With us they begin in New York after 

 the Tullv, in the Ithaca and Sigh Point zones (figures 5-7, plate 12) ; in 

 Iowa they appear in association with middle Devonian fauna-, and higher 

 up in the Carboniferous of the western part of the < tinent. 



The form which Kayser described as Rhynchonella procuboides (figure 1-'!, 

 plate 13) appeared below the true Cuboides zone in the middle Devonian 

 limestones. It is evidently the forerunner of Rhynchonella cuboides, and its 

 occurrence below is quite in consonance with the other facts, showing that 

 the fauna was indigenous to Europe, but thai all the representatives of the 

 fauna in New York sections first appeared with or above the Tullv limestone. 



The Bronteu8 flabelUfer, which occasionally appears in the European zone, 

 may be regarded as represented by Brontevs tullim, Hall. 



0ryplweu8 arachnoides, reported by Gosselet, is represented in our closely 

 allied form Dalmanites boothi, Green, but this as well as the Phacopa rona 

 are the apparent successors of the indigenous Hamilton species, and this is 

 near their latest, rather than their first, appearance. 



The corals and Rcci'ptuciiHtts nepluni, which are common in the lower 

 /one of the Belgian and Eifel sections, are more local in their character, hut 

 most of the corals are generally represented below and not often above. 



Thus it will he seen that the European fauna of the ( 'uboides zone is 

 represented almost completely hy the fauna which in New York begins with 

 the Tullv limestone. .Most of the specie- regarded a< characteristic <>f this 

 zone in Europe there appear also in lower zones, or are represented by closely 

 allied forms that may he safely regarded as their ancestors. 



These same species are conspicuous in the New York series by beginning 

 with the Tullv limestone and appearing frequently above, but showing no 

 closely allied species in the preceding middle Devonian. 



The Transition between the Hamilton am> the Ti i.i.v Faunas. 



I have examined a large amount of material from genuine Tullv limc- 

 stone, and also considerable more doubtfully referred to thai horizon. In 

 most places the Hamilton rock- are richly fossiliferous immediately under 



the Tullv limestone. These former, though mainly shales. itain limestone 



beds which in hand specimens are rarely distinguishable from thegenuiue 

 Tully above; bul the characteristic species of the Tullv arc warning, and 

 characteristic Hamilton Bpecies are abundant in them. Much confusion has 

 thus arisen, and the Tullv fauna, as reported in lists,* is very imperfect by 



; o. Williams in the R< porl ol the 8i oglsl of New JTork (Sixth 



Annual Report of the - t, Albany, 1887. p. 26) \ considerable number of the si les re- 



. .1 in iiii- ii-i l ha i oed in Oi Election made by the author of the li~t and And them 



containing them Indistinguishable from -i linens "Mni I al the same locality be- 



i uiiv limestone In limestone layers filled with llamiii"ii sp' ■ ]•■•-. bul never in the Tally 

 limestone Itself. 



