472 Mr. H. J. Carter on a new Species of Foraminifera. 



OpercuUna arahica {I. c. fig. 4, and ' Ami.' 1861, vol. viii. 

 pi. xvii. figs. 10, 11), where they are cemented togther by the 

 same kind of areolar calcareous structure, whose cells are so 

 minute, that they can only be just "seen in reflected light under 

 one-sixth-of-an-inch compound power with high ocular ; hence 

 its white appearance. 



After having described and figured such spicules in the cord 

 of OpercuUna arahica in 1852 ('Ann.' L c), Dr. Carpenter, 

 in 1859 (Phil. Trans, p. 25), stated that it was " due to the 

 peculiar manner in which the homogeneous substance of which 

 it (the marginal cord) is composed is traversed by the set 

 of canals that are correctly described by Mr. Carter as form- 

 ing the marginal plexus." To this I replied in 1861 ('Ann.' 

 I. c. p. 313) that this could not be the case, as in some speci- 

 mens the spicular structure existed over the septal spaces also, 

 where there is no marginal or any other kind of plexus. Then 

 Dr. Carpenter in 1862 (Introd. to the Study of Foram. 

 p. 257, footnote) rejoined, " So far from finding in this latter 

 statement any reason for modifying my own views, I draw 

 from it additional reason for believing that Mr. Carter has been 

 misled by the method of examination on which he seems to 

 place most reliance." 



Here the matter rested with Dr. Carpenter, but not with 

 myself, who, feeling convinced that I was right, could not 

 accept Dr. Carpenter's " views," viz. that solid fusiform bodies 

 such as I have described and figured {I. c), and of which I 

 still retain the preparation unimpaired, could be formed by a 

 " set of canals." Let any histologist try to conceive how a 

 plexus of canals, however disposed, could afford that continu- 

 ous surface which would be necessary to form a solid, fusiform, 

 calcareous body like the spicule above described, especially 

 over the septal spaces of OpercuUna, where no such plexus 

 exists ! 



So much for Dr. Carpenter's " views." Now let the above 

 description of this exquisite little organism, together with the 

 accompanying figure 2 (necessarily much enlarged to show the 

 relative size of the primary or embryonic cell, with the length 

 of the largest spicules), testify to the fact that, not only part, 

 but the lohole of the test may be formed of such spiculiform 

 bodies held together, as above stated, by minutely areolated 

 calcareous structure ; while, at the same time, it recalls to 

 mind the chitinous plates formed by the animal of Euglypha 

 itself for its own test, and not the heterogeneous material 

 brought from other localities by the animal of Lituola and the 

 arenaceous Difflugice for their tests respectively. 



Biidleigh-Salterton, 7th October, 1877. 



