56 Dr. G. C. Wallich on the Boring Powers of minute Annelids. 



deep-sea deposits actually taking place in our own day, and this 

 renders it particularly desirable that the attention of observers 

 should be directed towards them. I allude to the discovery 

 in the Chalk, by Mr. H. C. Sorby of Sheffield, of objects either 

 identical with them or so nearly identical as to leave no doubt 

 of their close affinity, and to the important additional evidence 

 herein furnished regarding the identity in origin of some of the 

 recent and more ancient oceanic deposits. It is not my wish at 

 present to do more than point out these facts. Whether it be 

 eventually shown that the association between these bodies and 

 the Foraminifera is purely fortuitous or otherwise, there cannot 

 be a doubt that they have some important office to perform in 

 the history of the deep-sea deposits, and that the investigation 

 of this office will materially assist us in clearing up the mystery 

 that surrounds the occurrence of similar objects in the Chalk. 



I have also to direct attention to some curious facts which 

 have presented themselves to my notice whilst investigating the 

 structure of certain Foraminiferous shells, and which illustrate, 

 in a remarkable manner, the soundness of the views first pro- 

 pounded by Professor Carpenter with reference to the transmu- 

 tation of many of the reputed species of these organisms. 



Having selected some well-developed Biloculina-she\h, I bi- 

 sected them in various planes, and found that the innermost 

 chamber of each individual — for segment it cannot in this case 

 properly be termed — was in reality a minute and perfect Miliola, 

 — this innermost chamber being, of course, the primordial cham- 

 ber of the group. As is well known, Biloculina is a symmetrically- 

 developed Foraminifer, the segments of which are arranged in 

 alternating series, but with their margins in the same plane. In 

 Miliola, on the other hand, the arrangement of the segments is 

 asymmetrical, the plane of growth being a revolving one. Wide 

 as the interval between the typical Miliolidce and Biloculina, at 

 first sight appears, the examples to which I refer show that 

 there is no true line of demarcation between them, and that the 

 one is neither more nor less than the primordial chamber of the 

 other ; whilst the future development of the primordial portion, 

 into what has heretofore been considered a typical adult Miliola 

 or a perfect Biloculina, depends wholly therefore on the condi- 

 tions under which its further growth is regulated. 



In the specimens under notice, the minute Miliolce were found 

 situated between the two earliest segments formed on the Bilo- 

 culina type; and within the boundary so constituted it was 

 placed, apparently, in an unattached state, but so closely pressed 

 on as to indicate that the growth of the new segments took place 

 upon the external surface of the primordial Miliola- chamber, 

 aud, as it were, on a mould. The minute Miliola, disposed with 



