Explanation of the plate. 



Figs. 1 — 4. MytMmeria flexuosa, Verr. & Smith from Figs. 9 — 10. Bathybela nudator, Locard, from st. 10. 



st. 101. Natural size. 1, right valve, 2, 

 dorsal region, 3, anterior region, 4, posterior 

 region. 



7. Pkoladomya fragilis, n. sp. from st. 70. 

 About twice natural size. 5, left valve, 6, 

 dorsal region, 7, anterior region. 



8. Troschelia berniclensls, King, var. elegans, 

 Jeffr. from st. 4. Natural size. 



9, shell, magnified about \ S U times, 10 

 sculpture, strongly magnified. 

 11 — 12. Surcula tenerrima, P. Fischer, from st. 10. 

 11. Shell, magnified about lVa times. 12 

 apex, magnified about 9 times. 

 Drawn with camera lucida. 



