Obolus 

 torrenti s. 



76 



Horizon and locality. Same as the proceeding. 



This species has a smoother surface than L. longovalis of the Etche- 

 minian (Lower) Fauna, but otherwise much resembles it. 



OBOLUS TORRENTIS, n. sp. PL VIII, fig. 1. 



A few examples of shells were found which from their form should 

 apparently be referred to the above genus. 



The valves are broadly orbicular and moderately arched. 



Ventral. Only an interior of a broken valve could be identified. It 

 shows a thickening of the margin toward the hinges. Interior. The 

 cardinal area is laterally extended and is striated ; the pedicle furrow is 

 distinct and depressed. 



Dorsal. An undersized exfoliated example was found, which is dis- 

 torted by compression longitudinally, and shows traces of concentric 

 ridges. There is a well-defined median sulcus on the mould extending 

 forward from near the hinge. 



Sculpture. Unknown, except as above noted. 



Size. Length of dorsal 5| mm. (probably shortened by pressure) ; 

 width 6 mm. A rim of an Obolus from the same terrane is 8 mm. across. 



This species is near the size of 0. triparilis of the Etcheminian Lower 

 Fauna, but is thinner, has a more obtuse beak to the ventral valve, and a 

 weaker hinge area to the dorsal valve. 



OSTRACODA. 



We have as yet only two forms that can be referred to this group of 

 crustaceans, one a very peculiar one, the other similar to oval carapaces 

 that are found in the beds of the overlying terrane. These will be found 

 described in connection with other ostracoda of the Etcheminian terrane. 



ETCHEMINIAN TERRANE. 

 ASSISE E. la. 



Assise holding This assise rests upon the effusive rocks of that last described. The 



Etehemin! lower part is a red amygdaloid that graduates upward into a red clay -slate, 



Fauna. which in its turn is covered by a bed of trap. The fossils are scarce and 



are found in the slate. A large Hyolithes occurs here, an Orthotheca and 



worm burrows, also a large Brachiopod. The fossils are badly preserved. 



