HELDERBERG DIVISION. 
349 
Pentamerus galeatus. 
Testacea. 
Strophomena impressa. 
Atrypa lacunosa. 
— varistriata. 
— semiplicata. 
Avicula naviformis. 
Strophomena rectilateris. 
— manticula. 
•— elongata. 
Euomphalus profundus. 
Lepocrinites gebhardi. 
Crinoidea. 
Astrocrinites pachydacty 
Two species of Atrypa from the Pentamerus limestone, in form like the Terebratula wil- 
soni, have been named by Prof. Vanuxem ; viz. the 
Atrypa wilsoni. Atrypa inflata.* 
8. Water-lime Group. 
Hydraulic limestone of Eaton. Part of No. 6 of Prof. Rodgers’ Reports. Part of Lower lime¬ 
stone of Becraft's mourdain, and of Helderberg series of former reports. 
Fig. 23. 
@8 
1. Orthis plicata. 
3. Tentaculites ornatus. 
5. Atrypa sulcata. 
2. Avicula rugosa. 
4. Littorina antiqua. 
6. Cylherina alta. 
The Water-lime group is composed of hydraulic and common limestone, of various degrees 
of purity and color, and contains several interesting mineral substances. Fossils, though 
common, are by no means so abundant as in the preceding calcareous strata. The rocks of 
this group are coextensive with the division, and are frequently seen in the Mamakating valley, 
where the other rocks of the Helderberg division are not visible, and they are observed to un¬ 
derlie the other rocks of the series throughout the whole of their extent. In Kingston, Hur¬ 
ley, Marbletown, Rochester, Saugerties, Catskill, Athens, Coxsackie, and New-Baltimore, 
they are remarkably well developed, and can be studied with ease, in consequence of their 
having been elevated at variable angles, by subterranean disturbances, since their original 
deposition. These disturbances have already been described, under the head of derangements 
Vide Geological Report of Third District, by Prof. Vanuxem, p. 119. 
