PALEOZOIC TIME — UPPER SILURIAN". 



645 



Tracks, probably of a Sea-worm, are represented by Fig. 744. These tracks 

 cover large surfaces of the Medhia sandstone, and are occasionally fOund in 

 the Oneida conglomerate. They are simply impressions, the material being 



74.5. 



744. 



Fig. T44, Harlania Kalli; 745, Cruziana (Rusophycus) bilobata (x 2). Hall. 



sandstone; and without structure internally, except the occasional occurrence 

 of parallel Or concentric layers, due to deposition in the depressions. Fig. 

 745 represents another form of track supposed to be of Molluscan origin. 



The following figures represent Corals, a Bryozoan, and a Graptolite of 

 the Clinton group : — Figs. 746, 747, one of the common Cyathophylloid Corals 



750 



CoEALS, GrEAPTOLlTE, BEYOZOAit. — Figs. 746, 747, Zaphrentis bilateralls ; 748, a, Palaeocyclus rotuloides ; 749, Ci 



Monticulipora ; 750, a, Graptolithus Clintonensis. HaU. 



of the genus Zaphrentis, the latter a view from above ; 748, a small disk- 

 shaped Coral ; 749, a minutely columnar coral-shaped Bryozoan of the genus 

 Monticulipora ; 750, a Graptolite ; 750 a, an enlarged view of the same. 



Other Clinton fossils are shown in Figs. 751-760. A finely reticulate 

 Bryozoan of the genus Fenestella (Fig. 751) is represented enlarged in 

 751 a. Fig. 752 is that of the characteristic Brachiopod, Pentamerus 

 oblongus, and opposite views of the hinge end of the cast of the interior 

 are given in Figs. 753, 753 a. Figs. 754, a represent the Brachiopod, 

 Dana's manual — 35 



