504 Dr. G. C. Wallich on a neAO Sessile Foraminifer. 



The associated Foraminifera (as determined by Professors 

 Rupert Jones and Parker) are : — 



BtlocuKna ringens (thick). Pulvinulina auricula (large). 



Lituola scorpiurus (nodosarine). Discorhina glohiilaris. 



I'extidaria sagittula. Xonionina scapha (large). 



agghdinans. striatopunctata (large). 



Cristellaria rotidata (large). Polysto^nella crispa (large). 



ariminensis (large). (Entosolenia marginata, var., 



curonata (large). G. C. W.) 



Professor Rupert Jones also informs me that he "cannot help 

 thinking the obscure lobulate spots in the centre of some of 

 the disks may be a very small primordial spire of the very 

 earhest-formed chambers, this being possible, probable, and 

 quite in accordance with Planorbuline characteristics." I 

 have completely failed to detect any thing like such an approach 

 to a spiral or minute chamber-like arrangement in two care- 

 fully dissected specimens which appeared most likely to exhibit 

 it, had it really been present. It is, however, quite possible, 

 as Prof. Jones says, that this structure may be disclosed when 

 a sufficiently large number of disks is examined. 



Height of the mature shell from ^V to -jV of an inch. 

 Diameter of disk about Jjj of an inch. 



EXPLA.NATION OF PLATE XX. 



Fig. 1. Erect view of a mature shell of Rupertia stabih's, showing the 



disk in profile and the slit-like aperture of the last-formed 



chamber. 

 Fig. 2. Oblique view of a specimen of the same, in which the neck is 



bent and the face of the disk presents itself. 

 Fig. .3. The most erect form in which this Foraminifer occurs, the 



aperture being on the opposite side to that depicted. 

 Fig. 4. Another specimen, showing the irregular growth sometimes met 



with. 

 Figs. 5 & 0. Young specimens, showing the contour of the primordial 



chamber. 

 Fig. 7. View from upper surface of the young specimen depicted in fig. 5, 



showing the position of the aperture. 

 Fig. 8. Disk of the same. 

 Figs. 9 & 10. Two views of a specimen in which two masses of mineral 



are firmly imbedded in the shell-substance. 

 Fig. 11. View from above of the last-formed chamber of an adult speci- 

 men, in which the arcuate and forked aperture was observed. 

 iFig. 12. A specimen in which the entire surface was thickly covered 



with extremely minute Globigerine and other foraminiferal 



shells and fi'agments of sponge-spicules. 

 Fig. 13. A perfectly " arenaceous " but broken specimen. No other 



specimen of this kind was discoverable in the material. 



