1849.] CARPENTER ON NUMMULINA, ORBITOLITES, ETC. 37 



Fig. 4. Fragment of Nummulina Icsvigata obtained by fracture in a direction per- 

 pendicular to the median plane ; showing the chambers, a to a', on that 

 plane, invested by successive layers above and below; b^b, the septa 

 between the chambers of the medial plane ; c, e, passages between the 

 inner margin of these septa and the outer margin of the preceding 

 whorl ; d, a chamber in the fourth whorl from the margin, invested 

 by four layers ; e, a chamber in the tenth whorl from the margin, in- 

 vested by ten layers ; /,/, investing layers ; g,g, spaces between these ; 

 h, h, intervening septa prolonged from the marginal septa. Magnified 

 20 diam. 



Fig. 5. Supposed animal of Nummulina, after MM. Joly and Leymerie. 



Fig. 6. Fragment of Nummulina laevigata, obtained by fracture through the central 

 plane, showing the doubleness of the septa through their whole course, 

 and the separation of the two layers at a, c, to surround the perfora- 

 tions ; showing also the minute canals in the walls of the chambers, and 

 the openings of these canals into their cavities ; and exhibiting the con- 

 tinuity of the marginal septa with those which divide and support the 

 investing layers. Magnified 24 diam. 



Fig. 7. Fragment of Nummulina laevigata, broken so as to display a marginal 

 septum and its perforations ; a, septum, marked with minute orifices ; 

 b, situation of principal passage, formed by the confluence of minuter 

 apertures ; e, the outer margin of the invested whorl. Magnified 45 diam. 



Fig. 8. Fragment of iVMmmM^ma Z«t72^a^a, fractured through the median plane and 

 at right angles with it, showing the perforations, «, a, &c., passing 

 continuously from the surface to the septa ; these passages being filled 

 up, in this specimen, by an infiltration of crystalline carbonate of lime. 

 Magnified 24 diam. 



Fig. 9. Transparent section of Orbitoides (from the same specimen as figs. 13 

 and 14) through the investing layers, in a direction parallel to the me- 

 dian plane ; showing the vertical perforations, a, a, filled up with opake 

 infiltration, and divided by dehcate septa into smaller apertures. Mag- 

 nified 60 diam. 



Fig. 10. Transparent section of Orbitoides (species undescribed) through the in- 

 vesting layers, in a direction parallel to the median plane, but near the 

 external surface, showing the large apertures, a, a, of the perforations, 

 filled up with opake infiltration. Magnified 60 diam. 



Fig. 11. Transparent section of Nummulina obtusa through the investing layers, 

 in a direction parallel to the median plane, showing the perforations, 



a, a, filled up with opake infiltration. Magnified 60 diam. 



Fig. 12. Transparent section of Nummidina complanata, in the same direction, 

 showing the perforations elongated into slits, a, a, divided by trans- 

 verse septa ; and the metamorphosis of the tubular shell into an appa- 

 rently prismatic structure, b, b. Magnified 90 diam. 



Fig. 13. Transparent section of Orbitoides (species undescribed), taken in a direc- 

 tion vertical to the median plane ; showing, a, the chambered layer 

 occupying that plane \ b,b, thick investing layers, the prolongations of 

 which extend beyond the central layer and inclose its margin, as seen 

 at e, and the vertical perforations, d, d, fiUed with opake infiltration. 

 Magnified 16 diam. 



Fig. 14. Transparent section from the same specimen, taken through the median 

 plane ; showing, a, a, the median chambered layer, and b, b, the investing 

 layers (a portion of which, more highly magnified, is shown in fig. 9). 

 Magnified 40 diam. 



Fig. 15. Transparent section of a portion of Nummulina Icevigata in a direction 

 perpendicular to the median plane (as in fig. 4) ; showing, a, a, the sheUy 

 layers cut through vertically, exhibiting their minutely tubular structure ; 



b, b, modification of that structure at the margins of the whorls ; c, e, 

 the marginal chambers ; d, d, the perforations infiltrated with trans- 

 parent crystalline deposit. Magnified 60 diam. 



Fig. 16. Transparent section of Nummidina Idevigata, in a direction parallel to the 

 median plane, to exhibit the structure of the shell inclosing the mar- 



