Manchester Memoirs, Vol. li. (1907), No. 9. 17 



specimens), they seem to be more characteristic of the 

 Polymorphinae. 



The specimens run into each other to such an extent 

 that it seems useless to give varietal names. Very 

 frequent. 



Note on the Absorption of the Septal 

 Walls in Polymorphinae. 



In my remarks on Polymorphina concava, Williamson 

 (page 14), I drew attention to the absorption of the septal 

 walls in that species. I believe that this peculiarity is 

 common, to a greater or less extent, to most, if not all of 

 the different species of Polymorphina that occur in the 

 Delos material, for, in the whole range, where the shells 

 are sufficiently transparent, I have not been able to 

 satisfy myself that this phenomenon is not present. In 

 very many cases the absorption is not complete, a neat 

 opening only, varying in length and width according to 

 the size and shape of the septal wall, having been dis- 

 solved out. 



This opening is often very apparent in the wall 

 between the two last chambers. I have broken open 

 some semi-opaque specimens from different species, and 

 in all cases the septal walls, or at least some of them, are 

 wholly, or partially destroyed. There are about twenty 

 specimens which I have brought together under the name 

 of Polymorphina oblonga, d'Orbigny (see PI. 2, fig. 20), 

 the tests of which are very clear. Now, in the majority 

 of these it is certain that some of the septal walls show 

 the opening in question, and probably the remainder 

 would be proved to possess it upon more careful examina- 

 tion. In looking at the Polymorphina, in my general 

 collection of Foraminifera from different localities, I find 



