williams.T FAUNAL DISSECTION OF THE DEVONIAN. 79 
as traces of the species occur at several points in the strata earlier and 
farther eastward, it is evident that the eastern migration began as 
early as the Tully limestone depression, which, for the region in which 
it is represented by a limestone, terminated the pure Tropidoleptus 
fauna. 
The full list of High Point is given in Dr. Clarke's paper (sec fore- 
going footnote), and the following species there listed are also 
reported from the Iowa Devonian. 
Table XVIL— The Pugnax pugnus fauna of High Point, New York. 
Camarotoechia contracta var. saxatilis. Sclrizophoria iowensis. 
Pugnax pugnus. Dalmanella infera. 
Atrypa reticularis. Orthothetes chemungensis. 
A. hystrix. Strophonella reversa. 
Spirifer orestes. Stropheodonta calvini. 
S. hungerfordi. S. variabilis. 
S. bimesialis. S. canace. 
S. subattenuatus. S. arcuata. 
Productella (dissimilis) hallana. Fistulipora occidens; 
These facts leave no doubt as to an intimate affinity existing 
between the High Point and associated faunas of New York and the 
Iowa Devonian fauna, as was claimed when I first called attention 
to the High Point fauna in 1883/' 
These species, common to the Iowa and Now York faunule, may be 
regarded as characteristic species of this Pugnax pugnus fauna. The 
fauna is mingled with the Tropidoleptus carinatus fauna to form 
the aggregate of the Ithaca formation. 1 in 1 at Ithaca it is not so 
strongly represented as at the High Point locality at the south end of 
Canandaigua Lake, in Ontario County. 
The study of the relations of the Cuboides fauna to a world-wide 
distribution led to the conception that affinities expressed by faunas 
may be due to migration rather than to direct evolution of the preva- 
lent fauna living in the region. This idea was set forth in the paper 
on the Calx tides fauna. h 
The observation that the Devonian faunas of Iowa are more 
closely akin to those of the Mackenzie River Valley and of Europe, and 
the fact that the faunas reported from South America are more closely 
akin to the faunas of the New York Hamilton than to the Euro- 
pean Devonian faunas, furnished the third clue to the interpreta- 
tion of fauna! history, viz, long periods of uniformity in the general 
geographical condition of the earth's surface have determined the 
local characteristics of the marine faunas, and a change in the fauna 
of a local province may indicate important geological change's involv- 
« On a remarkable fauna at the base of the Chemung group in New York: A.m. Jour. Sci., :i<l 
series, Vol. XXV, 1883, i>. 97. 
''The Cuboides zone and its fauna; a discussion of methods of corn -hit ion: liull. Geol.Soc.Am., 
Vol. I, 1890, pp. 4S1-5IK). 
