226 CRETACEOUS LAMELLIBRANCHIA. 
Ostrea Nilssoni has been referred by Bohm, Stolley, Grénwall, and Ravn to the 
genus Dimyodon, Munier-Chalmas.'| When describing Plicatula sigillina I remarked 
that although it belonged to a type distinct from the other Cretaceous species, yet 
it resembled the recent form Plicatula phillipinarum, Hantz. I have not seen 
the adductor impressions in any specimens of Plicatula sigillina, but nevertheless 
[ think that it is quite possible that the authors mentioned may be correct in 
referring this species to the genus Diinyodon, Munier-Chalmas. 
Dimyodon costatus, Gronwall, seems to be very closely related to D. Nilssoni. 
Page 152. Pecten Nilssoni, Goldf., Plate XLII, figs. 9, 10. Through the 
kindness of Mr. J. P. J. Ravn I have received specimens of P. Nilssoni from the 
Chalk of Faxe, and I am now able to state that I consider that the specimens 
from Trimingham, mentioned on page 152, and also another from the Act. quad- 
ratus zone of Hampshire (coll. R. M. Brydone), are referable to that species. 
1 In Fischer’s ‘ Manuel de Conchyliol.’ (1886), p. 957. 
