40 PAUEONTOLOOT OF NEW-YOBK. 



the rock is compact, we have no certain means of determining them. The latter species is 

 crystallized more frequently than the former, the stem of which is tubular and usually filled 

 with argillaceous matter. 



Fig. 1. Base or root of one of these fossils, with its diverijing and slightly ascending branches. The 



surface, not being worn, presents no marks of structure. 

 Fig. 1 a. A part of the specimen presents the longitudinal fibres, with very distant transverse fibres. 

 Fig. 1 b. A longitudinal section, passing nearly through the centre of the stem, showing the longitudinal 



and transverse fibres. 

 Fig. 1 e. Portion of two stems with the cuticle removed, showing the structure. 

 Fig. 1 d. Oblique sections near the termination of branches (the fructiferous portions?), presenting 



stellate or cruciform cells. 

 Fig. 1 a (in part), presents quadrangular cells, arranged diagonally to the direction of the stems. These 



forms may arise from weathering, or solution of cellular partitions in forms like 1 d. 



Position and locality. In the Birdseye limestone at Watertown and other places on the 

 Black river, and in the Champlain valley. Specimens like figs. 1 a and 1 b are not un- 

 conmion in some parts of the same rock in the Mohawk valley. (State Collection.) 



FOSSIL SHELLS OF THE BIRDSEYE LIMESTONE. 



Plate X. 



In some localities of the Birdseye limestone, where the rock is of a nature to admit of 

 their development, shells are very numerous, but it rarely happens that they are sufiiciently 

 distinct to admit of precise description. Several species appear to be identical with those 

 of the Trenton limestone ; but there are others, which, so far as we know at present, are 

 confined to this rock alone. 



I have presented the following forms, as indicating those which have more frequently 

 feJIen under my own observation, though I doubt not that a more numerous collection 

 could be made by farther investigations. The rock usually adheres so closely to the shell, 

 that the latter separates with it, and thus the external sculpture is obliterated. We are 

 compelled, therefore, to depend mainly on the foi;ra of the shells in distinguishing species. 

 Their position is almost entirely confined to the higher portions of the rock, which is 

 irregularly stratified, and much intermingled with shaly matter and fragments of the 

 Phytopsis. 



66. 1. MODIOLA? OBTUSA (». sp.). 

 Pi.. X. Fig. 1. 

 Single valve oblong, suboval, gradually narrowing towards the beak, convex ; anterior 

 extremity very obtuse. Some faint lines of growth, or striae, are perceptible. 



The specimen is a cast, nearly smooth, narrowing gradually towards the beak, and 

 slightly contracted before reaching the anterior extremity. 



Position and locality. In the upper part of the rock at Watertown, Jefferson county, 

 associated with Phytopsis. (State Collection.) 



