Explanation of Plate I. 
ure 1. Lichenalia concentrica Hall. (Page 5.) 
2. Monomorella cf. orbicularis Billings. 
Exfoliated and partly worn pedicle valve. (Page 5.) 
3 and 4. Orbiculoidea subplana (Hall) ? 
Pedicle? valves. (Page 5.) 
5. Orbiculoidea subplana (Hall) ? 
On telson of Eusarcus logani. (Page 5.) 
6. Orthis ? near tenuidens Hall. 
Brachial valve. (Page 6.) 
Illustrations natural size. 
