thetic Foraminifera from Somerset. 325 
clay from the coarser particles, although very carefully con- 
ducted, is sufficient to break up the excessively friable tests. 
Moulds of crystals observed in the other subarenaceous 
forms of the Rheetic Foraminifera are also present in the test 
of S. dispansa, but they do not seem to have been so largely 
utilized in this form. 
The test of this species, as previously noted, has a tendency 
to split horizontally along the median plane. This is owing 
to the restriction of the internal cavities exactly to the median 
portion of the test and to the marginal series of apertures, 
with which the chambers communicate. 
The above species was found in bed no. 3 of the Rheetic 
series at Wedmore, frequent ; bed no. 5, very common. 
22. Stacheia cuspidata, sp.n. (Pl. XII. figs. 9, 10.) 
“Plaques des Rayonnés,” Térquem and Berthelin, 1875, Mém. Soc. 
Géol. France, sér. 2, vol. x., Mém. no. 3, p. 105, pl. ix. figs. 3a—f. 
Test normally adherent, compressed, and irregularly 
discoid, but having the peripheral edge indented or cuspidate. 
The lower, attached surtace slightly concave, and the shell- 
wall of that surface thin, so that the figure of the central 
stellate cavity can be seen through the shell. Test some- 
what coarsely arenaceous, and the wall moderately thick and 
having a finely labyrinthic structure. The apertures are 
arranged almost as in S. dispansa, some orifices appearing on 
the peripheral margin, whilst others, curiously shaped and of 
a cuspid outline, are seen on the superior face of the test; 
in some cases these are lengthened out to an extraordinary 
degree. Diameter of test § inch (2°8 millim.), thickness of 
test zy inch (0°63 millim.), more or less. 
This is a discoidal variety closely allied to S. dispansa. 
It is fairly constant in its essential characters, and, unlike 
S. dispansa, always shows the adherent modification of the 
inferior surface, although no specimens were found actually 
attached to foreign objects. 
The forms figured by Terquem and Berthelin from the 
Lias, and referred to above, are very variable, but exhibit the 
essential features of the species. 
S. cuspidata occurs in bed no. 5 of the Rhetie series at 
Wedmore, frequent. 
