236 
J. 36.—Walk. f. 7\.—Turt. D. p. 120.—Discorsis. 
L. Macg. Ab. p. 34.—D. Vesicuuaris. Blain t. 5. 
Jf. 3. Compressed, white or yellowish, with a frosted 
appearance when much magnified, roundish or inclining 
to oblong, convex above and flat beneath; on the first 
volution are six or seven lobed joints separated by faint 
crescent shaped lines ; aperture extremely small. Mr- 
nute, attached to zoophytes. 
L. Concamerata. F, p, 233,—SeErputa C. Mont. 
Sup. p. 160. Nautitus. Dissrmixis, Turt. D.p. 120 
Suborbicular, compressed, flat beneath, slightly convex 
above, subpellucid, white, with three irregular volutions, 
the external having about nine glossy and tumid cells 
of unequal size but usually alternating large and small. 
Diam. 0,04....Devon. Differs from the last by pos- 
sessing infinitely more minute and numerous cells and 
in being devoid externally of that frosted appearance 
exhibited by it under the microscope. 
L. PutcHeita.—Discorzis P. Macg. Aberd. p. 
319. Orbicular, depressed, hyaline white, spiral, of 
numerous rather small, somewhat oblique regular cells 
in three and a half turns; lower surface rather convex, 
even, glossy ; the margin thin but rounded and very 
slightly lobate ; the unver surface convex, but with a 
