DR. W. B. CARPENTER ON ORBITOLITES TENUISSIMA. 573 



closed -in by a peneropline septum traversed by four passages ; b, second 

 chamber, divided by radial partition into orbiculine chamberlets ; c, third 

 chamber, not here separated from the second by a septum, and having only 

 one radial partition ; d, d, fourth chamber, having at d', d', lateral extensions 

 which begin to enclose the spiroloculine coil ; e, e, fifth chamber, with 

 lateral extensions, e, e, proceeding still further backwards ; these chambers, 

 and those that succeed them, divided by radial partitions into orbiculine 

 chamberlets. Magnified 75 diameters. 



MDCCCLXXXIIJ. 4 E 



