28 NEW YORK STATE MUSEUM 



PELECYPODA 



modiolopsis Hall 

 Modiolopsis aviculoides Hall. Pal. N. Y. 1847. 1:161 

 Two internal casts were found in the gray crystalline limestone 

 which are referred with some doubt to Modiolopsis avi- 

 culoides Hall, a little known species with which they agree 

 in the outline of their somewhat ventricose valves, oblique 

 cardinal lines, prominent umbones, and pointed anterior 

 extremity. Hall obtained his specimens from the shaly inter- 

 calated layers in the central part of the Trenton limestone at 

 Middle ville. (Group 7) 



whitella Ulrich 



Whitella ventricosa Hall sp. 

 E d m o n d i a ventricosa Hall. Pal. N. Y. 1847. 1 :155 

 A single large specimen of this species was found in a pebble 

 of black com/pact limestone. Edmondia ventricosa is 

 said by Hall to occur in the central and higher part of the Tren- 

 ton limestone at various localities of New York. White reports 

 it also from the Black river beds of the Poland limekiln section. 

 Its occurrence in the west is still doubtful. (Group 5) 



ctenodonta Salter 

 Ctenodonta ? sp. 

 A single cast of a lamellibranch was found on a black compact 

 limestone pebble, which in its outline is suggestive of a Cleido- 

 phorus, but it lacks the preumbonal clavicle impression, and 

 probably belongs to a Ctenodonta of the C. n a s u t a group. It 

 is too incomplete to allow exact determination. (Group 5) 



Ctenodonta cf. astartaeformis Salter 

 There were also found three specimens of a small Ctenodonta 

 of the C. (Nucula) 1 e v a t a group, which are comparable to 

 G. astartaeformis Salter, of the Canadian Trenton, 1 but, 

 judging from the description and figure of that species, seem to 

 differ from that by being wider anteriorly and having very 

 strongly developed growth varices which give to their surface 



i Can. organic remains. 1859. Decade 1, p. 39. 



