124 



through which the connecting necks uniting the segments of the soft 

 animal penetrate the septa; whilst the rows of larger circles (19, d) 

 are the extremities of the cul-de-sacs into which the marginal pro- 

 cesses of the soft animal are received. The central nucleus is pene- 

 trated by numerous large and somewhat irregular canals (19, e), 

 which pass vertically from the surface of the organism towards its 

 interior, terminating inferiorly, either as abrupt cul-de-sacs or taper- 

 ing off to a conical apex. Not unfrequently these passages are seen 

 to anastomose. Their internal surface is studded with a number of 

 very minute, projecting points, but exhibit no other appearance of 

 structure. 



The intervening pillars of solid, calcareous substance (19,/) are 

 seen to be very distinctly laminated ; the laminae being parallel to 

 each other and somewhat arched upwards, resembling the similar 

 lamellae, which have been described in the preceding pages as exist- 

 ing in Nonionina and Amphistegina. The descending passages bear 

 no relation to the position of the subjacent septa, neither do they 

 in any instance pass through any of the chambers, in order to reach 

 the more internal convolutions. They are strictly confined to 

 the solid, umbilical region, and where the chambers commence 

 they invariably terminate. All these points will serve to distinguish 

 the passages from the anomalous portions of Nummulina and Orbi- 

 toides, which are regarded as such by Dr. Carpenter.* I have no 

 doubt they are designed to facilitate the exit of the pseudopodia 

 from those convolutions which would otherwise be closed in between 

 the two lateral, calcareous nuclei. Guided by the additional light 

 obtained from Amphistegina, I conclude that the laminse seen in the 

 vertical sections (19,//), and which run parallel to the upper surface 

 of the organism, have been formed according to the plan suggested 

 in the case of the former example ; which idea, as the preceding 

 quotation has shown, is also in accordance with one of the two modes 

 which I considered capable of explaining the structure when the pre- 

 vious memoir was written, though at that time I regarded it as the 

 less probable of the two. 



The Rotalia Beccarii, so common on our shores, also exhibits a 

 peculiarity of structure which appears to involve the necessity for 

 adopting a similar explanation of the way in which the Foraminifera 

 make these external additions to their shells. Owing to the trochoid 



* I believe that this preparation of P. crispa, along with the analogous ones, 

 represented by figs. 4, 5 and 6, will be found to throw some valuable light upon these 

 obscure but interesting forms, the elucidation of which is now in such able hands. 



