43 Ithaca Group 43 



occurring at nearly ever}' station, and usually associated with P. 

 Jilosa. It varies greatly in form and size. 



The specimens referred to this species include many which 

 correspond to Hall's figures of P. maxima, but which seem to 

 be only variations of the P. constriRa type. 



Palceoneilo co7istrina \a.r . Jlexicosa (Conrad) Hall. 

 Ithaca group. — Hall. 



Palcsoneilo filosa Con. . 



This is a common species of the Portage and Ithaca groups. 

 It shows comparatively little tendency to variation. Well pre- 

 served specimens show distin(5l, fine striae between the coarser 

 ones on the posterior part of the shell, similar to P. fecunda. 



Palcsoneilo plana Hall. 



This species occurs in the Ithaca group, but is much less 

 common than the two preceding. 



PalcEoneilo emarginataf (Conrad) Hall. 



Two imperfect specimens from the Ithaca group are referred 

 to this species. 



Leda diversa Hall. 



This species is rather common in the Portage and Ithaca groups. 



Leda curtaf Meek. 



Lower Portage. — H. S. Williams. 



Leda perstriata Hall. 



Upper Spirifer Icevis zone. — H. S. Williams. 



Modioviorpha subalata var. chemungensis Hall. 



This is one of the most abundant species in the Ithaca group. 



Modiomorpha subalata Hall. 



Some specimens from the Portage and Ithaca groups corre- 

 spond to M. subalata of the Hamilton. 



Modiomorpha concentrica Hall. 



A few specimens have been found in the Ithaca group. 



Modiomoipha co^nplanata Hall. 



From the lower part of the Ithaca group. — H. S. Williams. 



Modiomorpha negleBaf Hall. 



A single specimen from station 7-10 is referred to this species. 



