206 Mr. H. J. Carter on the Polytremata. 



form of the ovum itself. The latter is probably spherical, as 

 in most other Foraminifera ; and its earliest embryonic form 

 may also be a spherical cell, as in NummuUtes &c. ('Annals,' 

 1861, vol. viii. pi. xvii. figs. 2 o, 12 e, & 15 e) ; but in the thin 

 Australian OrhitoUtes, of which I have several specimens 

 in which the chambers are charged with embryos, the latter are 

 all elliptical elongate. 



It is true that in the supposed embryos of the broken chamber 

 in Polytrema halaniforme we have a conical fixed form, con- 

 sisting of a corrugated transparent envelope enclosing minute- 

 granular opaque material, and the appearance of an apical 

 aperture — all of which is found in the single embryo developed 

 just outside the test ; yet the more advanced state of the latter 

 and the differentiation of parts, with tlie presence of a filament 

 of foreign material projecting fromone of its apertures (fig. 8,/), 

 is much more suggestive of its real nature than that of the 

 " embryos in the broken chambers." 



Finally, the presence of more than one aperture about the 

 envelope of the single embryo seems to point out that in the 

 fully developed test there may be also more than one, through 

 which the sponge-spicules &c. are drawn into the interior — a 

 fact which the projecting of spicules through certain portions 

 of the surface of the full-grown test seems to indicate, al- 

 though it is impossible to state this with certainty, from the 

 rough treatment to which my specimens have been subjected 

 having caused a great part of their foraminated areas to be 

 irregularly broken out. Such apertures would of course be 

 subsidiary, and formed, as they are in Polytrema minia- 

 ceum^ by an accidental destruction here and there of one of 

 the foraminated interstices of the network on the surface. 



Not possessing more than full-grown specimens of Poly- 

 trema halaniforme (fig. 7) and the early embryonic form above 

 described (fig. 8), I have no means of following its grada- 

 tionary development further than is indicated by the structui*e 

 itself of the former, which is above given. 



Note on Parkeria. 



Through the kindness of Mr. W. J. Sollas, I became pos- 

 sessed of a spheroidal specimen of Parheria, 1| inch in dia- 

 meter, from the neighbourhood of Cambridge, on the 1st of 

 February, some days after my MS. on the Polytremata had 

 been sent to the press. This specimen, when it reached me, was 

 in three pieces, consisting of the two halves of the sphere minus 

 an entire central slice, which had been ground down to great 

 thinness and mounted for microscopical examination. Most 



