88 NEW YORK STATE MUSEUM 



in the Grande Greve specimens. They might in this respect be regarded 

 as constituting a stable expression of the species of which the corrugated 

 form is a variety. It is to be noted, however, that corrugation is often an 

 incipient condition disappearing in late growth, and that hence the uncorru- 

 gated form is tachygenic. The shell is very common at certain localities. 



Localities. Matagamon lake, east side, i mile above dam ; Telos lake, 

 Blind Cove point ; Moosehead lake, 7 miles north of Kineo Jackman farm. 



Hipparionyx proximus Vanuxem 



Plate 21, figure 12 

 See pt i, p. 200 



The specimens of this highly characteristic Oriskany species are alto- 

 gether like those occurring in the sands of New York and the limestones 

 of the Forillon, Gaspe, though to our observation never attaining so large 

 size. 



Localities. Matagamon lake, northeast of Matagamon mountain ; 

 Cunningham's camp, 4 miles from Matagamon lake. 



Rhipidomella musculosa Hall van Solaris Clarke 



Plate 21, figures 8-u 

 Set pt I, p. 201 



Rhipidomella musculosa Hall var. Solaris Clarke. N. Y. State Mus. Bui. 

 107. 1907. p.284 



These are all small shells with the enormous adductor scar in a state of 

 high development. The shells are somewhat less circular, more transverse 

 than in the New York and Grande Greve Oriskany specimens of R . m u s- 

 c u 1 o s a, but their specific identity is not greatly veiled. 



Localities. Moosehead lake, Baker Brook point ; Brassua lake, east 

 side ; Moose river at Stony brook, Me. 



Dalmanella cf. circularis (Sowerby) 



Plate 21, figures 5-7 



We have here some well defined internal casts of both valves of a 

 plano-convex species. I do not attempt to further identify them than to 

 institute the above comparison which may be extended to D . p 1 a n o c o n- 

 vexa Hall of the Helderbergian. 



Locality, Jackman farm. 



Pholidops terminalis Hall 



See pt ), p. 213 



Occasional at Baker Brook point : Mooseliead lake. 



