382 PROCEEDINGS OF SECTION C. 



Hyperammina vagans the tube normally commences with a bulbous 

 or drop-shaped primordial chamber ; in Girvanella, in one species at 

 least, it commences with a long segmented series {g) of ovoid and some- 

 what irregular chambers or cells, which are doub, fully calcareous, and 

 probably originally of the nature of cellulose. The evenness of the 

 granular structure of the walls of the tube -cell in Girvanella is not 

 characteristic of the tests of the rhizopoda, which, in tha areniceous 

 group, are formed of adventitious sand -grains. The branching of the 

 tube as seen in Girvanella is unknown in the group of rhizopods to 

 which Hyperammina belongs. The oblique septation of the*early cells 

 in Girvanella is also quite at variance with that seen in the foramini- 

 feral genu 5 in question ; and the irregularity in the shape and size of 

 the cells or segments is practically unknown in that group of organisms. 



EVIDENCE FOR THE RELATIONSHIP OF GIRVANELLA 

 WITH THE THALLOPEYTES. 

 In the examples of Girvanella, which possess fine tubes of an 

 indefinite length, it has been difficult to discover the earlier stages of 

 the organism ; but in a more coarsely tubular form, found in some 

 abundance in the Victorian limestones, and which is evidently more 

 or less allied to G. pisolitica, Wethered, there seems invariably to be 

 a somewhat extended series of ovoid cells, generally repent upon crinoid 

 fragments, which at first sight the writer was inclined to regard as a 

 minute modification of the foraminifer known as Gypsina. On closer 

 examination under the higher powers of the microscope, it was seen 

 that the cell- walls of this organic structure were non-perf orate, thick- 

 walled, chitinous in appearance, and peculiarly wrinkled or cracked 

 along the diagonals of the subquadrate cells, reminding one of the 

 aspect of certain modern vegetable cell-structures when undergoing 

 shrinkage. A similar system of shrinkage cracks may also be observed 

 in the cell walls of " macrospores " or sporangia found in spore-coals, 

 which also seem to be produced by the drying of the original vegetable 

 structure. This phenomenon lends strong support to the conjecture 

 that these cells of the initial stages in certain Girvanellce are, like the 

 macrospores, of vegetable origin. The diagonal shrinkage of the cell- 

 walls in the Girvanella above described further reminds one of a similar 

 structure seen in Rothpletz's figures of " Schlau^he mit Sporangien " 

 in SphcBroco(lium.{h) The initial series of ovoid cells has already been 

 figured by Wethered, (?') but not alluded to by that author : they occur 

 in a section of a pisolitic granuh formed principally of the tubes of 

 G. pisnlitica from the Inferior Oolite of Cheltenham, England. One of 

 the series of cells of a:i example from the Tyers River, Victoria, measures 

 a little over a millimetre in length, whilst the average maximum and 

 minimum axes of the cells themselves measure .089 mm. and .055 mm. 

 respectively. Frequently the initial series appears arrested in its further 

 growth : but wheie this continues it shows a nassaee into more and 



(g) An exception to this, however, is shown in Wethered's figure of the bulbous 

 commencement in an example of G. pisolitica (Wethered, '90, pi. xi., fig. 3). 

 (/t) Rothpletz ('91), pi. XVI., figs. 4, 5. {i) Wethered ('89), pi. vi., fig. 10. 



