42 FORAMINIFERA OF THE CRAG. 
FissukINA DILATATA, Seguenza, 1862. For. Monot. Mioc. Messin., p. 65, pl. 2, fig. 21. 
—  LA&VIs, Id. Ib:, p. 66, pl. 2; figs: 22, 23. 
—  Romerrensis, Id. Ib., fig. 24. 
—  ORBIGNYANA, La. Ib., figs. 25, 26. 
— MARGINATA, Id. ibe hee: 27, 28. 
—  sULcaTa, Id. Ib., p. 67, pl. 2, fig. 29. 
— TUBULOSA, Id. Ib., p. 68, pl. 2, figs. 36, 37. 
— Costa, Id. Ib., p. 69, pl. 2, fig. 38. 
— ELEGANS, Id. Ib., fig. 39. 
—  GEMELLARII, Id. Ib., p. 70, pl. 2, fig. 45. 
—  REGOLARIS, Td. Ib., p. 71, pl. 2, fig. 46. 
—  Sarroril, Id. Ib., fig. 47. 
—  LysE.uit, Td. Ib., figs. 48, 49. 
—  Rizzaz, Id. Ib., fig. 50. 
AMYGDALINA TRUNCATA, Id. Ib. p. 73, pl. 2, figs. 52, 53. 
LaGENna MARGINATA, Brady, 1864. Trans. Linn. Soc., vol. xxiv. p. 472. 
— sULCATA, var. (ENTOSOLENIA) MARGINATA, P. and J., 1865. Phil. Trans., vol. 
clv, p. 355, pl. 13, figs. 42—44; pl. 16, fig. 12 
Characters.—Shell orbicular, compressed, with a more or less prominent marginal 
ridge or carina. ‘lube either Ectosolenian or Entosolenian. Aperture oval or slit-like. 
Surface smooth. Colour white or dirty white. Length {th or less to 3th inch. 
Under the general name Zagena marginata are included a large number of flattened 
forms, variable in shape, generally Entosolenian, but sometimes Ectosolenian with a long 
delicate neck. ‘This compressed shape is usually associated with a trenchant margin, 
sometimes slightly apiculated, and sometimes dentate or rowelled (as in Williamson’s 
‘ Monograph,’ pl. 1, figs. 21 a, 25, 26), reminding us of the keel of certain Cristellarie. 
Occasionally, in large well-developed specimens of ZL. marginata (recent and fossil) the 
margin is composed of a large predominant rib, strengthened by a pair of smaller costz 
(L. fasciata, Keger, &c.), showing that, as in other Foraminifera, especially the Nodosarine 
group, the exogenous coste gather themselves to the margins, the rest of the surface 
becoming less and less ornamented. ‘The pseudopodial pores also usually affect the 
neighbourhood of the thickened margin in these flattened forms, just as they follow the 
ridges of LZ. striato-punctata. Occasionally the pseudopodia have perforated the whole 
surface, either sparsely, or freely, as we have seen in specimens from the Indian Sea. 
In some rare specimens from the Coral-reefs of Australia, and fossil at Bordeaux, we 
see the pseudopodia begin to enter the shell-wall near the centre, and then burrow 
radially to escape near the margin, the shell-surface being perfectly smooth and as 
polished as glass (LZ. radiato-marginata, P. & J.). 
The intussuscepted neck-tube in LZ. marginata is generally more or less oblique, 
somewhat trumpet-shaped, and of varying length. ‘The apparent difference in the 
setting on of the mouth, which we formerly thought we could detect, between Lxtosolenia 
and Lagena proper (‘Annals Nat. Hist.,’ 2nd ser., vol. xix, p. 279) does not really 
