DEVONIAN SECTION OF ITHACA, N. Y. 109 
upon paleontological evidence has been called the Van Etten zone of 
Tropidoleptus, for the expression of it seen in the rocks about Van 
Etten near drainage level. It was not known to contain Tro pidolepius 
in 1886, when I published the paper on the classification of the Upper 
Devonian.t Since then the fauna has been detected in several places. 
When well developed it contains the following species: Tvopido- 
leptus carinatus; Rhipidomella vanuxemi; Productella spinulicosta; 
Ambocelia umbonata; Lingula complanata; Spirijfer marcyi; Del- 
thyris mesicostalis. 
Specimens of the latter species in external appearance are often 
very similar to the ordinary type of Spirijer mucronatus (= pennatus) 
of the Hamilton group. 
Associated with these diagnostic species the fauna also contains 
species of the following genera, viz: Leiorhynchus, Leptodesma, 
Palaeoneilo, Grammysia, Modiomorpha (Cypricardella is not gener- 
ally with it), Bellerophon, Coleolus, Pleurotomaria, Loxonema, 
Platyceras and occasionally Orbiculoidea, Chonetes and Camaro- 
toechia. 
One of the best places to see the fauna is in the ravine above White 
Church in the Dryden quadrangle, where it lies about two hundred 
feet below the base of the Chemung. On passing eastward the rocks 
of the upper part of the Nunda become more and more fossiliferous, 
and other species come in and probably other zones of the Tropido- 
leptus fauna; but in the Watkins Glen quadrangle this fossiliferous 
zone is frequently seen in the more eastern sections below the typical 
Chemung fauna, carrying several species which are common above, 
but never any of the species indicated above as diagnostic Chemung 
forms. 
In the sections about Ithaca, traces of this same fauna are seen 
near the base of the Ithaca member in the zone I referred to in 1882? 
as a recurring Hamilton fauna. Since that paper was written the 
Tro pidoleptus carinatus has been noted at the same horizon. 
When these recurrences take place in the Watkins Glen quad- 
rangle below the range of Delthyris mesicostalis, but above the Hamil- 
t Proc. A. A. A. Soc., Vol. XXXIV (1886), pp. 222 ff. 
2““The Recurrence of Faunas in the Devonian Rocks of New York,” Proc. 
A. A. A. Soc., Vol. XXX (1882), p. 189. 
