LAGENIDA. 29 
to a very variable amount of lateral compression, either on two, three, or four sides. Aperture 
usually single; in the exceptional distomatous forms the two orifices are at opposite 
ends of the shell. Shell-wall perforated by numerous very minute foramina.’ ‘Texture, 
hyaline. 
For our views of the relationship of Zagena, in its manifold variations, see the ‘Philos. 
Transact.,’ 1865, vol. clv, p. 345, &c. The accompanying table of the distribution of 
fossil Lagene will be of interest to geologists, who can also refer to a general list of fossil 
and recent Layene, by Prof. Reuss, in the ‘Sitzungsb. Akad. Wiss. Wien.,’ 1862, vol. 
miviep. 317. 
In our table we have arranged the Laygene according to our scheme of the prominent 
forms, as indicated in ‘ Phil. “Trans.,’ doc. cv¢., p. 348, introducing some that do not occur 
fossil, to make the series complete; and we have introduced into the table materials from 
the works of Reuss, Seguenza, and others, having made their nomenclature conformable 
with ours. 
1 The keel of the compressed Lagene, and the marginal ribs of the angular varieties, are formed of 
“the supplementary skeleton,” or secondary shell, containing what has been termed “ the canal-system.” 
Occasionally, as in Lagena tubifero-squamosa, P. & J. (‘ Phil. Trans-,’ 1865, p. 420), the whole surface is 
coated with this extra shell-growth. The circular cavities, or “ lacunze,”’ in the keel of L. ornata, shown 
in Williamson’s ‘Monograph,’ pl. 1, fig. 24, are really continuous with the minute pseudopodial perfo- 
rations of the shell-wall, usually by delicate bundles of tubuli; and they communicate with the exterior by 
a coarse pseudopodial tube. 
