a 
482 H. B. Brady—Sitlurian Lagene. 
flattened on two sides, probably the result of pressure, and present 
an oval instead of a circular transverse section. A few specimens 
of smaller size (Fig. 4) are more elongate and fusiform, the two ends 
being drawn out nearly equally and the inferior extremity bluntly 
pointed. The surface of the fossils is generally rough, owing partly 
to the corrosion of the test and partly to the adhesion of minute 
fragments of the matrix. The aperture is simple and circular, often 
indistinct owing to the nature of the infiltrated material. The 
specimens vary much in point of size, measuring from 3; to jy inch 
(roughly from 1 to 2 millim.) in length, and from @y to #s inch 
(0-42 to 1-4 mm.) in transverse diameter. 
None of this set exhibit the long tapering neck which gives to the 
typical Lagena levis its characteristic flask-like contour. It is true 
that the neck may have existed; but if so, it is remarkable that it 
has not in any case been preserved either in the form of external 
shell or internal cast, inasmuch as it remains uninjured in smaller 
and more delicate specimens from a not far distant locality. When 
first examined, it was thought possible, chiefly on account of their 
size, that some of these little fossils might turn out to be Polymor- 
phing, as they bear considerable external resemblance to certain 
species of the “Globuline” section of that genus; but. neither on 
the surface nor in the interior have any traces of septation been dis- 
covered. After careful comparison it does not appear that the 
dimensions of even the larger examples need be a serious objection 
to their acceptance as Lagene. It is true that either amongst recent 
or fossil Lagene, shells measuring #5 inch (1:2 mm.) are very rare; 
but the “Challenger” dredgings furnished at least one representa- 
tive of this genus (Lagena marginata), the diameter of which includ- 
ing the wing was just about the same as that of the largest of the 
Silurian specimens, namely, 7; inch (2 mm.). 
That some of the specimens under notice are only casts, and that 
the others have had the exterior much weathered and corroded, 
admits of no doubt; nevertheless, thin sections of the smoother more 
perfect individuals show unmistakable remains of the original test 
(Fig. 3). Where least altered this is seen to be a tolerably homo- 
geneous wall about 73> inch (0:086 mm.) in thickness. Treated 
with weak acid both the test and its subcrystalline contents dissolve 
rapidly, leaving only a faint trace of siliceous residue. 
Compared with the foregoing, the specimens collected by Mr. J. 
Smith, which number about twenty in all, are of exceedingly small 
dimensions. In point of size they have nothing to distinguish them 
from average recent examples of the genus. They are mostly of the 
simple flask-shaped type, with rounded base and long tapering neck 
(Figs. 6—10), with which we are familiar as Lagena levis. They 
vary in length from 5's to zs inch (0:28 to 0°57 mm). A few have 
the pointed base (Fig. 5) which characterizes the varietal form 
known as L. clavata. They are for the most part casts, and it is 
difficult to say whether any portion of the original shell-wall remains, 
though transparent sections (Fig. 10) show in places a more or less 
distinct external layer, differing in texture from the inner subcrystal- 
