:.!.] 



we are rompl.'t<>ly in the -lark as to its probable affinities. The other species 

 referred to this genii- l>y Billing fall more or less naturally into one or the other of 

 the generic groups above outlined and will be referred to in discussing the genera 



further on. 



\\ - ought perhaps to have included the illy characterized genus Conchopeltis, 

 \V ;t . iKin^r the I'iil. ./nil- I'.if./li'l.r, especially since the types of the second 



species described by the author of the genus came from the Lower Silurian of 

 Minnesota. As neither is illustrated, we must rely upon Walcott's description of the 

 genus. That gives us to understand that it is founded on conical patelliform 

 univalves having the apex subcentral and the surface radially striated. So far as it 

 goes it agrees with Scentlla and that indeed is the position we assign to C. minneso- 



T considerable trouble Prof. N. H. Winchell succeeded in having drawings 

 prepared of C. <iltrna(a, the first species described by Walcott, and the one therefore 

 to be regarded as the type of the genus. As may be seen from the accompanying 

 figures, the slopes in this species are divided into four, slightly convex, lobe-like 



.ncktprlti* aUemata W:i nton limestone, Trenton Falls, N. Y. Two views pre- 



pared fron - nal types of the specie* (now preserved In the Cambridge Museum) showing the four 



lobe-like division* of the shell, Its form and surface workings. 



parts by an equal number of narrow depressions radiating from the apex. So far as 

 we are aware, none of the other described patelliform shells exhibit such a lobing 

 <.f the shell, and we are therefore quite uncertain as to the affinities of the genus 

 W,> ,houM mention, however, that a similar peculiarity occurs in three new species 

 of an undescribed genus of patelliform shells, two of them from the Cincinnati 

 rocks, the other from the iMvonian. In these there is a strong transverse division 

 passing immediately above the beak and separating a lobe corresponding to the 

 upper one in our figure of Conchopelti*. l>ut the rest of the shell is not lobed. The 

 outer layer of these shells is minutely and beautifully punctate. 



