Mr. H.J. Carter on the Structure of the larger Foraminifera. 249 



spherule, and at others much larger than the largest. Those 

 which are observed about the test externally are white when 

 dry, so that they already contain calcareous matter. Sometimes 

 the spherule or primary cell begins to develope a second while 

 still in the parent-chamber (I have seen this in one of the cham- 

 bers in the outer turn of Nummulites Ramondi j indeed, I have 

 the section showing it) ; and then the young one evidently be- 

 comes too large for passage through the ordinary chambers. In 

 this case it would seem that a special opening is formed for their 

 exit through the spiral lamina ; for holes exist here and there in 

 this part of the test, which, from their rounded edges, indicate 

 that they were made by the animal. Not unfrequently these are 

 formed opposite the great spiral canals. 



Mode of Development. — The spherule, having left the parent, 

 becomes the primary cell of the new being, and putting forth a 

 stolon, produces another chamber, and so on until a certain 

 number are formed, which are arranged horizontally around the 

 first, and the Operculina is developed. The stolon therefore forms 

 part of the canal-system, and the chambers are in this manner 

 developed from it. As development progresses, the chambers 

 which bud from the margin of the cord attain their largest size, 

 and then begin to diminish again, until they end in almost 

 nothing, and are closed in, as before stated, by the ben ding- 

 down of the marginal cord and its union with the preceding 

 turn, when the test is thus hermetically sealed and its form 

 completed. The union between the chambers at their bases is 

 probably only filamentous ; for the chambers do not here com- 

 municate with each other, while the calcareous septa which di- 

 vide them are frequently united to the marginal cord ; and if 

 not in direct contact, they are always more or less scolloped, 

 indicating a round filamentous layer of the sarcode which pre- 

 viously existed between them and the cord. Besides, we shall see 

 presently that the development of the test is frequently continued 

 without the presence of the chambers; so there can be no 

 question that all other structures are developed from the sarcode 

 of the canal- system, or from the filamentous sarcode, connected, 

 of course, originally with a nucleated cell. Hence the filamentous 

 sarcode becomes analogous to the mycelium of Fungi, and being 

 rhizopodous, is united, through the Sponges, to the fungal 

 parasitic animals which inhabit the cells of Algae and are pro- 

 pagated by monociliated AmcebEe, and, through the latter, to the 

 true Fungi, which are propagated by defined sporules. 



Nummulites is nothing but a more complicated form of the 

 Operculina tj'pe. The chambers bud from the margin of the 

 cord, and extend outwards and inwards until they reach the 

 level of the margin of the last turn and the umbilicus of the 



