,xxii. COJ^CHY LI A— DITHYR J. 



3. plicata, lamelloso-plicata, antici dilatata. 



with laminar plaits, dilated at the anterior end. 



5. HiATELLA. 



1. minuta, postich truncala areolata. 



truncate with an impression at the hinder end. 



2. oblonga, poslice rotundata, areola nulla. 



rounded at the hinder end, without impression. 



6. Petricola. 

 1. Irus, Petricola. 



7. Venekupis. 

 1. perforans, Venernpis. 



8. Mya. 



1. turncata, antich truncata, dente mutico. 



truncate at the anterior end, with the tooth 

 simple. 



3. ovalis, antich 7-oliui(ta(a, dente Jlexuoso. 



rounded at the anterior end, with the tooth 

 flexuous. 



2- arenaria, antich rotundata, dente denticuluto. 



rounded at the anterior end, with a denticle on 

 the tooth. 



9. Lyonsia. 

 J. striata, Lyonsia. 



