159 



Plate X. Fig. 28. It is rather rough and scabrous ; partly from the 

 removal of some small portions of its surface, and partly from the adhe- 

 rence of some of its calcareous matrix. On being viewed with a lens, 

 it presents the appearance Plate X. Fig. 30. The tubes are seen to be 

 distinct ; and, where the outer surface has been removed, the conca- 

 merations are perceived, resulting from the interposition of very nu- 

 merous and minute septa, transversely disposed. These tubes narrow 

 as they approach to their terminations, and as may be seen in Fig. 29, 

 which represents one of the ends of the fossil magnified, the end of each 

 tube overlaps that of the preceding. That this is the case, and that 

 these tubes are placed perpendicularly round the centre, is evident, from 

 the appearance of the longitudinal section, Fig. 31, in which a section 

 is seen of the central and surrounding tubes, divided into compartments 

 by their small and numerous septa. 



From this examination it appears, that round the small first-formed 

 tube, or chamber, successive increasing columnar tubes were disposed, 

 folding over each other at their ends. Whether these several tubes 

 were, as it is most probable, internally connected with each other, or 

 not; or whether the chambers communicated, or not, with each other, 

 by a siphuncle ; are questions, which must remain to be answered by 

 the examination of some more illustrative specimen. Like some of the 

 nummulites, this body, when polished, has more the appearance of bone 

 than of shell. From this circumstance, as well as from the number and 

 appearance of its septa, I am disposed to consider this body as approxi- 

 mating nearer to the nummulite than to any other fossil. 



LXXXIV. Discorbis. A spiral discoidal univalve ; the turns all con- 

 tiguous, uncovered, and perceptible. The septa transverse, whole, and 

 frequent. 



Lamarck, who has seen these shells only fossil, supposes them to be 

 known only in that state, and wishes that circumstance to be pointed 

 out by the termination of the name of the genus, Discorbites. It is said 



