LAGENIDA. 45 
set of forms, leading from the common round-based varieties towards the distomatous 
series. 
These smooth apiculate Zagene, or smooth subvarieties of LZ. caudata, D’Orb., are 
found in many places in company with the common Zagene, and they are fossil in the 
‘Tertiary strata. One or two small specimens only have occurred to us in the Crag of 
Sutton. 
11. Lacena craciniima, Seguvenza. Plate I, figs. 36, 37. 
Miniota Lavis, Ehrenberg (parte), 1845. Mikrogeol., part 2, p. 22, pl. 26, fig. 2. 
Lacuna Lavis, Parker and Jones, 1857. Ann. N. Hist., 2nd ser., vol. xix, p. 278, 
pl. 11, fig. 23. 
AMPHORINA ACUMINATA, Seguenza, 1862. Foram. Monotal. Mioc. Messin., p. 51, 
pl. I; fig.35. 
— CYLINDRACEA, Td. Ib., fig. 36. 
— GRACILLIMA, Id. Ib., fig. 37. 
— DISTORTA, Id. ib: ps b2,)pl_aly fig. 38. 
LAGENA SULCATA, var. DISTOMA-PoLITA, Parker and Jones, 1865. Phil. Trans., vol. clv, 
p. 357, pl. 13, fig. 21; pl. 18, fig. 8. 
Characters —Shell much elongated, fusiform, distomatous, often twisted or curved. 
Both extremities subulate. Surface smooth. The hyaline texture of the young shell 
becomes opaque white in older specimens. 
Length 3th to 2th inch 
This may be regarded as the distomatous form, corresponding to Z. /evis in the 
single-mouthed series. Although it has been found elsewhere, both in recent and fossil 
condition, we have never seen specimens approaching those from the Crag in point of size, 
except from the Red Sea and Australia; indeed, those in Mr. Wood’s collection from 
Sutton are the largest Zagene with which we are acquainted. 
Fig. 37, Plate I, represents a portion of the shell more highly magnified, and shows 
very beautifully its foraminated structure. It may be constantly noticed, in examining 
the shells of Zagene under high powers, that the amount of perforation varies with the 
thickness of the wall ; that in the, thimner, more delicate portions the foramina are few and 
indistinct, whilst in those places in which it assumes stouter proportions the surface 
is closely studded with dots indicating the open ends of the tubuli. 
Distomatous Zagene are by no means common. ‘The best-known form has an elon- 
gated, straight-sided shell, with delicate, parallel, longitudinal strize (Zagena distoma, P. 
and J.), occasionally found in deepest soundings in the Northern Seas. 
Seguenza, in his ‘ Monografia dei Foraminiferi Monotalamici delle Marne Mioceniche 
Messinesi,’ figures four smooth-shelled double-mouthed specimens with as many different 
specific names. Three of these are symmetrical, and one of them (fig. 37) the exact counter- 
