104 W. J. Sol/as — The Genus Wehhina. 
not tuberculate. — Formation, Cambridge Greensand. — Locality, Cam- 
bridgesbire. 
2. W. tuberculata, mihi, Figs. 4 to 9. — Surface of test omamented by 
a number of tubercles irregularly dispersed, generally hemispherical 
and depressed, resembling tbe rivet-heads on an iron girder, but sotne- 
times conical and transversely truncated, average diameter 0 , 00115 // , 
lieigbt OOOOS". In some specimens tbe tubercles appear to be larger 
and more numerous than in otbers. A section of tliis speoies, includ- 
ing some instructive longitudinal sections of its tubercles, is repre- 
sented in Fig. 7. 
From an examination of these it will be seen that eacb of tbe 
bosses of the exterior is but tbe superficial portion of a structure 
wliicb enters deeply into the test. This structure bas tbe form of a 
double cone, such as would be produced by two cones fusing to- 
getlier by a common base, the outer and shorter one rising into a 
tubercle on the exterior, the longer and inner one reaching inwards, 
nearly, but not quite to tbe interior face of tbe test. The longitudi- 
nal axis of tbis skittle-shaped colurnn or double cone is occupied by 
a canal about 00009 of an ineh in diameter, simple and cylindrical 
in tbe exterior cone, but in the interior one constricted and dilated 
alternately eitber in an annular or spiral fasbion, as shown by the 
waved outline of its margins in section. 
Exteriorly tbe surface of tbe test is slightly raised to form a 
mound about tbe projecting cone, and internally tbe substance of the 
test immediately imbedding tbe penetrating cone is traversed by 
tubuli as elsewbere, which, however, stop short of the cone itself. 
Formation, Cambridge Greensand. Locality, Cambridgeshire. 
Bemarlcs . — As the contents of the Cambridge Greensand bed have 
been subjected to very considerable attrition, it is just barely pos- 
sible that W. Icevis is simply W. tuberculata, witb its outer tubercles 
worn off. The smooth, beautifully finished appearance of tbe former 
species does not lend any Support to tbis conjecture however, nor do 
careful sections made across its sbell exhibit tbe interior ends of the 
tubercular columns, which of course would remain after tbe exterior 
parts bad been worn away. The conclusiveness of this latter critical 
test is, however, somewhat diminished by the difficulty of obtaining 
complete and perfect slices of such minute objects as these forms. I 
have not been able myself to obtain a section of more tbau an arc of 
the wall of W. Icevis, and the completeness of tbe section of W. tuber- 
culata shown in Fig. 7 is entirely due to the accident of its having 
been pi-eserved imbedded in hard coprolite, which afl’orded it a firm 
support on all sides in the process of grinding down. 
Alliances . — The minuteness of the tubulation would appear to ally 
these forms to the Rotaline series of Foraminifera, and the irregulär 
method of their growth to Planorbulina, to the coarse perforations 
and projecting points of which genus the perforated columns of 
Webbina tuberculata present indeed a certain sort of resemblance ; in 
external form there is an absolute identity of cbaracter between W. 
Icevis and Trochammina irregnlaris. 
Summary . — That the tubulated Webbina, simulating the truly arena- 
ceous Trochammina, should be found in tolerable abundance in the 
