10 
and in certain of the strata we find great quantities of lignite 
derived from coniferous wood. Numerous cones occur in 
the lignite beds, and occasionally leaf-bearing twigs are 
found. The cones belong to the genus Gernitzia, and some of 
the branches apparently represent the genus Ulmania. 
Enveloped in this vast amount of vegetable matter, the 
fragments of quartz referred to seem to have been very much 
corroded by the humic acid generated in its decomposition 
Pror. D, S. Martin exhibited a number of Primordial 
fossils, from Troy, N. Y., some of which are newly described, 
and made some remarks upon the mode of their occurrence. 
The recent exploration of these beds, and the discovery of 
several new species, are due to Mr. 8. W. Ford, of Troy (from 
whom the specimens shown had been received); though the 
locality had been known for many years, to some extent, and 
species had been described from it in the State Paleontology. 
‘These, however, were supposed to be of Hudson age, and 
their true horizon has only of late been determined. The 
rocks occur in a series of ridges, with a slight eastward dip, 
and a strike about parallel to the Hudson river, on the ele- 
vated plateau immediately east of the city of Troy. They 
consist of sandstones and shales, with intercalated beds of 
limestone, in which latter the fossils are found. Whether the 
several parallel ridges, with their similar dip and strike, are 
due to faults, or to sharp eroded folds, Mr. Ford has not been 
able to satisfy himself, owing to the drift which occupies the 
intervening depressions. 
The species exhibited comprised Agnostus lobatus and 
Olenellus asaphoides among trilobites, Obolella desquamata, 
Metoptoma rugosa, and the following pteropods, Hyolithes 
(Theca) triangularis, and its operculum, H. impar, Ford, 
(new), and Hyolithellus micans, Billings, (also new) with 
opercula. The latter in this species are perfectly circular in 
outline, and not oval, as they were represented in the figures 
which accompanied the original description. They are ex- 
tremely well-defined and characteristic, with their péculiar 
muscular impression, resembling an eight-pointed star, the 
