474 
Aug. F. Foerste 
found near Cabot’s Head, on the shore of Lake Huron. Clinton; 
or Niagara formation (at present called Cataract formation). 
A. Murray, Esq. 
From the accompanying figure (fig. 28) it is evident that in 
addition to the plates mentioned, plates 4 and 9 also are present. 
The column is round, and tapers distally. Only the proximal 
columnals are present. Reticulate markings are not in evidence 
on the plates of the theca, but the specimen evidently is more or 
less weathered. The height of the complete theca probably was 
about 16.5 mm., agreeing in this respect quite closely with Brocko- 
cystis clintonensis, Parks, from the same horizon. From the latter 
species, Brockocystis huronensis appears to differ chiefly in its 
more convex thecal plates. Evidently more material is necessary 
before Brockocystis huronensis can be considered an established 
species. 
Judging from present knowledge, Brockocystis is confined to the 
Cataract formation, while Lepadocystis is known only from the 
upper Richmond. 
