No. 1. — Fossil Sponges of the Flint Nodules in the Lower Cretaceous 
of Texas. By J. A. MERRILL." 
Tun following investigation was undertaken as thesis work in the 
course in Paleontology in Harvard University, at the suggestion of the 
instructor, Dr. R. T. Jackson. As the study proceeded, its importance 
became more apparent and it was thought advisable to extend the work 
somewhat and publish it. With the advice and assistance of Professor 
N. S. Shaler, therefore, careful revision has been made and the results 
here presented. So faras I have been able to ascertain, the minuto 
structure of the cretaceous flints of America has never been studied 
except in a general way, and nothing whatever has been published on 
the microscopic organisms composing them. The field is therefore 
a large as well as a fascinating one, and this effort is intended 
only as a beginning of what is hoped will prove a fruitful line of 
inquiry. The flint nodules from which specimens were taken for 
study were collected in a quarry near Austin, Texas, and brought to 
Cambridge by Mr. Edward E. Cauthorne. They vary greatly in shape 
and size ; and, owing, perhaps, to small areas of calcite scattered through 
the mass, they vary somewhat in hardness. The hardness is often 
greater than that of glass, and the flint will generally scratch glass. Іп 
shape they are spherical, cylindrical, or flat; and in size they vary from 
two inches to a foot or more in diameter. Тһе color із a dense black, 
with white or gray spots mixed irregularly through it, varying in size 
from microscopic to that of a pin-head, These spots are generally 
replacements of organic remains, and, when such, are, in all cases that I 
examined, ehalcedonic silica; the larger ones showing the concentric 
structure characteristic of chalcedony. Some of them, however, have 
shapes so irregular and outlines so indefinite, that they cannot be re- 
ferred to any particular organic form, although they are most likely 
replacements. All the spots of calcite examined are small and 
indefinite in form and outline. They are called calcite because of 
their behavior in polarized light. The outside of the nodule is com- 
posed of a layer of chalk about one quarter to three quarters of an inch 
1 Contributions from the Geological Laboratory of the Museum of Comparative 
Zoology, in charge of М. S. Shaler. 
VOL. XXVIII. — NO. 1. 1 
