178 MR. THOMAS ALCOCK ON QUESTIONS REGARDING 



but on the shores of this country they have not hitherto, 

 so far as I am aware, been found anywhere in plenty, 

 though they occur scantily in many localities; and their 

 unusual abundance on this part of the west coast of Ireland 

 may probably be due, therefore, to the influence of the 

 Gulf Stream. Another point of interest about these two 

 forms is, that they always occur together ; and this fact, 

 with a general agreement in their character, has led to a 

 suspicion, long since entertained, I believe, by Prof. Wil- 

 liamson, that there is some very close relationship between 

 them. I find the Orbulina, or single-sphered form, of very 

 different sizes, the largest being as much as six times the 

 diameter of the smallest, with every possible intermediate 

 gradation; and, considering that the shell is needed for 

 protection and support, but can only be made of the exact 

 size of the body on which it is moulded, while that body 

 will continue to grow, I cannot avoid the conclusion that, 

 in this case, as often as a larger shell is required the 

 animal must withdraw itself entirely from the old one and 

 cast it off. The coating of sarcode, therefore, which is 

 usually found on the outside of the shell, is more than a 

 mere result of the coalescence of the bases of the pseudo- 

 podia, for it consists of the whole additional growth of the 

 animal since the shell was formed, and will continually in- 

 crease in quantity, until at last a new one is required. I 

 have one specimen where a large and perfect globe has 

 the segment of another globe of similar size attached 

 to one side of it, and I can account for this appearance 

 in no other way than by supposing that instead of the 

 animal having cast its shell as usual, the external sarcode 

 has in this case collected itself into as much of a sphere as 

 the circumstances would allow, on the outside of the ori- 

 ginal globe, and has there covered itself with a supplemen- 

 tary shell. 



But a consequence of this view — that the single-cham- 



