266 The American Geologist. Ap"1. 19^-1- 
8. — Pentraplis periitsus Forskal. 
Only one specimen found but that excellently preserved. Reported 
by Flint from straits of Yucatatn. 
9. — Orbitolites niarginalis Lam'k. 
One very perfect specimen found and numerous fragments. Re- 
ported from Florida by Flint. 
10. — Uvigerina angulosa Williamson. 
Frequent. Reported on the west coast by Flint. 
II. — Sagrina striata Schwager. 
One specimen only. Flint does not report this species but the Chal- 
lenger dredged it off the So. American coast. 
12. — Truvcatiilina zvuellersiorfi Schwager. 
Frequent. Reported from the gulf of Mexico by Flint. 
13. — Anomalina coronata Parker and Jones. 
Rare. Reported by Flint off the coa«t of Georgia. 
14. — Nonionrma scapha Fichtel and Moll. 
Frequent. Reported from Panama bay and the coast of Yucatan 
by Flint. 
Bo'ston Society of Natural History. Joseph a. cushman. 
New York Academy of Sciences. The Section of Geology and 
Mineralogy held its regular meeting January 18, 1904, with the chairman, 
professor James F. Kemp, presiding. In the absence of the secretary, 
Dr. A. A. Julien was appointed secretaty pro tern, and papers were pre- 
sented by Dr. Irving and Mr. Wilson, abstracts of which follow : 
"Microscopic Structure and Origin of Certain StyloHtic Structures 
in Limestone," by J. D. Irving. From an extended examination of styl- 
olitic limestones collected in Indiana and Wyoming, mainly by Mr. M. L. 
Fuller and himself, the author has drawn the following conclusions re- 
garding the origin of the peculiar structures : 
1. They were initiated along a thin layer in limestone and have been 
produced by the interpenetration of the limestone material on either side 
of this clay seam. 
2. They are entirely independent of the presence of fossils existing in 
the rock, for they occur equally in those portions of the rock where fos- 
sils are absent and where they are present. 
3. They were not formed by metamorphic agencies, or by the weight 
of overlying strata, or by other causes which would tend to distort and 
crush the rock material. 
4. They were produced by a cause which operated on the material of 
the rock while it was yet unconsolidated, and in a condition approxi- 
mating that which obtained at the time of deposition. 
5. They originated under great pressure, the rock material being 
sufficiently soft to allow the bending of individual stylolites, and j'et 
potentially rigid so that organisms were sharply sheared oflf while held 
ill the soft matrix. 
While the cause of the pressure and the manner in which it had op- 
erated to produce these structures ha\-e not 1)o-.mi determined, the author 
