560 



Forty- fifth Report on the State Museum. 



Eichwald, was taken by Volborth as the type of Acritis. The 

 latter species is imperfectly known. Mickwitz regards both 

 Aulonotreta and Acritis as synomyms of Oboltjs). 



Pedicle-valve with a broad, subquadrate muscular scar crossed 

 on its posterior portion by a transverse band connecting what 

 appear to be cardinal scars. 



Aulonotreta antiquissima. After Volborth. 

 Fig. 246.— Interior of pedicle- valve. Fig. 247. — Interior of brachial valve. 



In the brachial valve are two subcircular scars in the median 

 region just within the posterior margin. 



Type, Aulonotreta antiquissima, Eichwald. Cambrian. 



Schmidtia, Yolborth. 1869. 



Pedicle-valve with a broad, centrally-grooved cardinal area, 

 and, in the middle of the valve, two obliquely oval muscular 

 impressions separated by an elevated ridge. In the brachial 



Schmidtia celata. (Volborth.) 

 Fig. 248.— Interior of pedicle-valve. Fig. 249.— Interior of brachial valve. 



valve is also a low median ridge and a single pair of oval 

 impressions. 



Type, Schmidtia celata. Cambrian (Unguliten-sohiohten). 



Mickwitz considers this a synonym for Obolus. 



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