REPORT ON THE FORAMINIFERA. 
349 
30 fathoms to 1900 fathoms; and fossil specimens appear at almost every geological age 
from the beginning of the Liassic period to the present time. 
Webbina clavata, Jones and Parker (PI. XLI. figs. 12-16). 
Trochammina irregularis clavata, Jones and Parker, 1860, Quart. Journ. Gcol. Soc., vol. xvi. 
p. 304. 
,, irregularis (pars), Carpenter, 1862, Introd. Foram., p. 142, pi. xi. fig. 6. 
Webbina irregularis clavata, Jones, Parker, and Brady, 1866, Monogr. Foram. Crag, p. 26, No. 3. 
„ clavata, Brady, 1882, Proc. Roy. Soc. Edin., vol. xi. p. 711. 
Test consisting typically of an oval or pyriform, convex, tent-like chamber, with a 
tube of indefinite length issuing from the narrow end ; both chamber and- tube adherent, 
the open extremity of the latter serving as the aperture. Shell- wall finely arenaceous, 
smooth and glossy externally, of rich reddish-brown colour. Longer diameter of the 
chamber, from ^>th to ^th inch (0'5 to 1‘0 mm.). 
Apart from its ruddy-brown colour and polished surface, which are very distinctive 
features, the tent-like construction of the test of Webbina clavata is its most important 
and most easily recognised character. The only organism with which the species is likely 
to be confounded is Hyperammina vcigans. These two forms resemble each other to the 
extent that both are parasitic, and that they consist alike of a chamber with a tube of 
indefinite length issuing from it ; but in Hyperammina both chamber and tube are 
complete in themselves and invest the animal on all sides ; whilst in Webbina the 
chamber is only a patelloid tent, and the tube semicylindrical, so that the test, which has 
no wall of its own on the inferior side, is closed-in by the surface of the body to which it 
is adherent. 
The tubular portion grows to an indefinite length, but under all circumstances retains 
its semicylindrical adherent condition, and, in the absence of larger objects, attaches 
itself to Globigerince or other bodies of microscopical dimensions, as seen in fig. 16. 
In some instances, in addition to the tubulated orifice, a small aperture may be 
detected in the convex face of the chamber, (fig. 14), but this is comparatively rare ; and 
occasionally the detached test exhibits a minute aperture on the inferior edge, at the 
broader end, as appears in fig. 15. 
In localities at which the species abounds the tests are often thrown together in 
colonies, several individuals overlying one another. An example of this sort is depicted 
in fig. 13, and an even larger number of chambers may sometimes be found piled 
together the same way. 
The geographical distribution of Webbina clavata \ extends over a very large area, and 
its bathymetrical range includes every depth from about 100 to nearly 2000 fathoms, 
the finest specimens being found at less than 1000 fathoms. It is common in the 
(ZOOL. CHALL. EXP. — PART XXII. 1883.) Y 45 
