Notes on Spirifera Parryana. 27 



dence, Iowa; but seems to have some doubt as to whether it 

 occurs at Rock Island, Illinois, or not. The fact is that S. asfcra 

 as a characteristic species of the S. farryana platform may 

 be found near Rock Island; but so far as I know it has never 

 been found, and is not likely to be found, at Independence. 

 Prof. Whitheld, who has had abundant opportunity for know- 

 ing whereof he speaks, is undoubtedly correct when (Geology 

 of Wisconsin, Vol. IV, page 332,) he says that the type 

 specimens of this species described and figured by Prof. Hall 

 were "from rocks of Devonian age at Rock Island, Illinois." 



The locahties at which S. farryami occurs in Scott and 

 Muscatine counties have been frequently referred to in this 

 paper. It remains only to mention one or two other localities 

 at which the species has been recognized. Crushed and more 

 or less broken and distorted specimens are found along the 

 Iowa river near Iowa City. Near Linder's boat-house they 

 are comparatively abundant. Here we have the same group- 

 ing of species as in Muscatine county, except that the Cyrtina 

 umhonata is replaced by a small form of C. hamiltonensis^ 

 probably the variety recta. A short distance further up the 

 river there are exposures of rocks with S. pcnnata and its 

 associated variety of Atrypa asfera. 



Regarding Buffalo and Pine Creek as the central and 

 typical localities for S. -parryana^ the most distant station at 

 which the species has been recognized in Iowa is at an old 

 railway cut and embankment a few miles north of Fayette. 

 As might be expected the individuals here depart most widely 

 from the typical form of the species; none are exactly like the 

 average forms from Muscatine county. In some extreme 

 cases the hinge area is narrow and strongly concave, and the 

 beak of the ventral valve is brought almost directly behind that 

 of the dorsal. The pHcations are in all cases more rounded 

 and elevated than in specimens farther south. The fine radiat- 

 ing and concentric strije remain the same, and the traces of 

 two rudimentary plications in the sinus are frequently quite 

 pronounced. At Fayette there are none of the short-hinged, 

 wide-areaed forms that are frequently seen at Pine Creek. 



