102 The American Geologist. Aufust, i89i 
Wisconsin is one of the areas where the life of 0. jtropinqua- 
tulUensis was continued into association with a t^'pical Hamilton 
fauna. There Rhynchonella cuhoides-venustula is absent, but the 
reappearance of (>. propinqua-tuUiensis in the Tally limestone is 
quite as likely due to its return eastward as to an immigration from 
the east. We do not follow Mr. Williams in the statement that 
"Its appearance in the following zone in New York, i. e. , the 
Ithaca formation and the High Point fauna in Ontario county, 
suggests that the fauna to which it belongs is more directly asso- 
ciated with what follows than with the New York Hamilton fauna " 
(p. 492). The High Point species is not a Schizophoria of this 
rigid specific type but is susceptible to very considerable variation 
and is more nearly like the form described b}- Meek as 0. Mac- 
farlanii. Moreover neither the Ithaca formation nor the High 
Point fauna constitutes the zone next following the Tull}' lime- 
stone in New York. 
Strophodonta perplana Conrad (sp.) var. tnUiensis Williams. 
The author makes an evidently good separation of a small form 
of this species with mucronate cardinal extremities, but the cor- 
relative importance given to the variation is far overwrought. He 
sa3'S (p. 493): "The second species, S. perplana var. tulliensis, 
is a mutation (sic) of the race which begins in StropJiomena alter- 
nata in the Trenton stage. " Undoubtedl}'^ Strophomena alternata 
is a representative of the stock from which the strophodontoid 
line emanated, but the "race" did certainly not have its begin- 
ning in this Trenton species.* Attention is called to the fact that 
at the base of the Devonian the " race ," referred to develops into 
two "races" (p. 403), one a thin flat form, t3'pified b}' S. perplana 
Conrad, which is said to be "an American t\-pe and is seen with 
variations all through our Devonian, but it is not described in the 
European Devonian." Nevertheless the t3'pe is well known in the 
European Devonian and is represented b}' Strophomena explanata 
Sowerby, as identified by Kayser who states that it is known to 
him from all horizons of the Rhenish lower Devonian and is no- 
where especiall}' rare, t 
The other "race, " which is really the normal line of stropho- 
dontoid development, maintains the convexo-concave contour. 
"This is the Orthis interstr talis Phillips, of the European Devo- 
nian and Strophomena Incvqnistriata Conrad, of the New York 
*Lcptiena incra88(^it(t and L. faschita Hall, of the Chazy limestones are 
species congeneric with Stropliotncnn (iltcrnata. 
fDie Fauna des Hauptquartzits, p. 102, 1889. 
