ON OOLITES AND SPHERULITES 605 
Since, at present, the original papers are inaccessible to me I 
cannot judge the degree of probability of this suggestion. It is, 
of course, possible that frequent interruptions in the normal process 
of growth of the odlitic grains, caused by a stirring of the calcareous 
muds during storms, permitted the Ophthalmidia to attach them- 
selves to the grains and thereby to participate in their growth. 
2. The second case comprises odlites in the formation of which 
filamentous algae are supposed to have had an active part. Such 
odlites were, for instance, recently described by Van Tuyl from the 
Ordovician of Iowa.t They contain in abundance “minute sinuous 
fibers similar to those which characterize the Girvanella type of 
calcareous algae.’’ In odlites from the shores of the Red Sea, Roth- 
pletz found “peculiar vermiform, and not rarely dichotomously 
branching, canals that are filled up with calcite.’ In fresh-water 
springs and pools threadlike Schizophyceae are usually found 
associated in great numbers with the primitive types which cause 
the separation of the lime carbonate. Rothpletz, therefore, con- 
sidered the vermiform structures of the odlites as “ threadlike algae 
which were, of course, not themselves immediately concerned in 
the odlite formation, but by the company in which they lived were 
imprisoned with it.” Since Van Tuyl states expressly that his 
odlites showed in addition to the supposed calcareous algae ‘‘ good 
concentric and radial structure,” there can be little doubt but that 
Rothpletz’ interpretation may be applied to them directly. Similar 
canals might, however, also be produced by boring algae or fungi, 
the ramified canals of which are found permeating larger shells 
and pebbles as well as shells of Foraminifera in size comparable to 
the odlites.3 
Relation of algae to oolites.—The réle which Rothpletz assigned 
to such Schizophyceae as Gloeocapsa and Glceothece in the formation 
IF. M. Van Tuyl, Science, N.S., XLIII (1916), 171; Jour. Geol., XXIV (1916), 
792-97. 
2 Rothpletz, Am. Geologist, X, 280. 
3 J. E. Duerden, “Boring Algae as Agents in the Disintegration of Corals,” Bull. 
Amer. Mus. Nat. Hist., XVI (1902), 323-24. They were also described from Ordovician 
Foraminifera and from numerous Siluric fossils (see F. B. Loomis, ‘‘Siluric Fungi from 
Western New York,” Bull. N.Y. State Mus., VIII (1900), No. 39, 223-26, especially 
Fig. 3 on Pl. 16). 
