78 Profs. Parker and Jones on Ovulites margaritula. 



forated are not the tubules of a hyaline Foraminifer (though 

 homologous with them), but the passages for large bulbous 

 threads of sarcode, such as in Dactylopora pass from the in- 

 ternal mass, at regular intervals, as single or multiple stolon- 

 like threads. These may or may not swell into ganglion-like 

 beads, occupying chamberlets in the thickness of the wall, and 

 communicating with the exterior, more or less freely, by fur- 

 ther threads of sarcode. In Ovulites the thread-like process 

 was swollen before it reached the surface, and either commu- 

 nicated with the exterior by a small aperture in the shell, or 

 was covered in on the outside. Each of these little processes 

 from the large inner sarcodic mass was invested with its own 

 shell-matter, forming a minute, subhexagonal, perforated 

 block, fitting side by side, with hundreds of others, to form 

 the ovoidal or cylindrical shell. This may be open at both 

 ends, like a distomatous Lagena. 



The external pores in Ovulites are elliptical or suboblong, 

 smaller, in proportion, than in Dactylopora and more irregu- 

 lar, and they are bounded by the sutural subhexagonal out- 

 lines, or areolation, above indicated. In other words, the 

 general wall consists of more or less six-sided, close-fitting 

 plates, set edge to edge, and each pierced with an elliptical 

 aperture, leading to a round chamber and narrow passage, 

 opening on the inner side. The subhexagonal blocks are 

 homologous with the longitudinally perforated needle-prisms 

 of Nummulina^ in which each pseudopodial thread is invested 

 with its prismatic coat (as Dr. Carpenter has explained, ' In- 

 trod. Foram.' p. 256) ; and the whole, fitting closely side by 

 side, constitute the shell-wall. In Glohigerina, also, this 

 prismatic structure is well known, and has been figured by 

 Dr. Wallich in ' The Atlantic Sea-bed,' part i. pi. 6, and 

 in his 'Biology oi Glohigerina'' (1876, 8vo, Van Voorst). 

 Here the thick and deeply areolated shell, shown by fig. 6, 

 is homologous 'with some Dactyloporce^ in which the bulbous 

 threads of sarcode, penetrating the shell, thicken into beads 

 (see fig. 9, Orhulina) ; and these external beads, becoming 

 continuous, invest all the structure (fig. 7), and produce a 

 secondary shell-growth, not only as in Orhulina and Glohige- 

 rina^ but in Pulviriulina, Lagena even, and many other Fora- 

 minifers. The isolation of small pyi-iform or flask-like 

 morsels of sarcode in the shell-wall of Glohigerina {op. cit. 

 p. 75, figs. 17, 18, 19; see also 'Proc. Roy. Soc.,' February 

 1875, p. 236) is evidently homologous with the enclosure of 

 sarcode lobes in the walls of the Dactyloporidaj. Dr. Carpen- 

 ter has already remarked that in Dactylopora and Glohigerina 

 there is a corresponding absence of stolonal communication 



