REPORT OH THE FORAMINIEERA. 
143 
aperture, and the shape of the valvular tooth, as well as in the degree of angularity of 
the outer margin of the shell, has been dwelt upon by many writers ; and the case has 
been so fully stated by Williamson (Rec. For. Gt. Br., p. 80) that there is little 
left to be said on the subject. It is sufficient to repeat that in the genus Biloculina 
neither the shape of the aperture nor the roundness or irregularity of the margin furnishes 
any character sufficiently distinctive to be of more than comparative value to the 
systematist. It is convenient to recognise certain forms that may be roughly dis- 
tinguished from each other by their general contour, such as Biloculina bulloides, the 
typical Biloculina ringens, and Biloculina depressa, together with a few others that 
appear to be somewhat more definite local varieties ; but the fact remains, that from end 
to end of the generic series the variation is one of degree only. With slight exception 
in the matter of surface ornamentation, no new character makes its appearance, aud the 
successive links in the chain only differ amongst themselves in the greater or less 
development of a few features common to the whole. 
Biloculina ringens abounds in almost every sea, and at almost every depth hitherto 
explored, from shore-pools between tide-marks to nearly 3000 fathoms. 
As a fossil it is found with other Miliolcc in Tertiary deposits as far back as the 
Eocene of the Paris Basin. 
Biloculina ringens, var. denticulata, nov. (PL III. figs. 4, 5). 
General contour proportionately longer and margin somewhat more angular than in 
the typical Biloculina ringens. The inferior portion of the peripheral margin of the last 
chamber more or less toothed. Length, ^rcl inch (0‘75 mm.). 
The dentate condition of the inferior portion of the margin of the test varies much in 
degree ; otherwise the specimens are very uniform, not only in general contour, but in the 
shape of the aperture, in size, and in other minor characters. The distribution is limited 
to certain comparatively narrow areas, and the distinctive features appear to be those of 
a tolerably well-marked local variety rather than of a species, even in the lax interpre- 
tation of the term permissible in speaking of Foraminifera. 
Biloculina clenticulata belongs to the coral-reef fauna. The best specimens have been 
obtained from the Honolulu Reefs, 40 fathoms; off Tongatabu, Friendly Islands, 18 
fathoms; and off the Admiralty Islands, 15 to 20 fathoms. A very similar variety, but 
without the indentations of the margin, occurs off St. Vincent, Cape de Verde Islands, 11 
fathoms ; and off Kanclavu, Fiji, 610 fathoms. 
Biloculina ringens, var. striolata, nov. (PI. III. figs. 7, 8). 
General characters the same as those of var. clenticulata, but having in addition a surface 
ornamentation of slightly irregular, raised, longitudinal striae over the inferior portion of 
the shell, especially of the penultimate chamber. Length, ^rd inch (0'7 5 mm.). 
