-Description of new Lower Silurian Sponges. — Ulrich. 233 
well as professor Calvin appeared to know it when he wrote 
his article of June, 1883, I could have added, that the place in 
the series for Spirifer parryana fauna to appear, is between 
\)asi Spirifera pennata iSiWix^ oi the typical Hamilton lime- 
stones, and the fauna with Spirifer a wMtneyi and Spirifera 
hungerfordi. 
But the confusion as to which rocks really belong to the 
"Kinderhook group" of Meek and Worthen, a confusion 
which, it now appears, professor Calvin shared with some of 
us who lived outside of Iowa, made it impossible to place con- 
fidence in the strictness of reference for the fossils reported. 
The representatives of "/S'. whitneyi^'' and '^ S. Tiungerfovdil^'' 
wherever they are recognizable, from the Ural mountains, from 
Russia, from Germany, from Northern France, from Spain, 
from Belgium, from England, and from New York and along 
the Appalachian, are always associated with species found at 
the close of the middle or base of the upper Devonian. The 
Russian, German, and French geologists more generally re- 
gard this fauna as the first fauna of the upper Devonian, to 
which the name '■'■ Frasnien''^ is quite commonly applied. The 
English, on account of the great disturbance of the rocks dur- 
ing and after the Devonian, have no satisfactory means of de- 
termining the precise sequence of faunas, and it is also prob- 
able that the South Devonshire limestones were continuous, 
without change, till after the stage represented in other re- 
gions by the earlier part of the upper Devonian deposits. 
The homotaxial relation of the Rockford shale fauna, and 
that of the "yellow sandstones" of Muscatine Co., Iowa, if the 
species have been correctly reported, is with the faunas of the 
"Ithaca group" of New York and the East, and of the "Fras- 
nien Etage" of the northern part of Europe and Asia, and not 
with strictly middle Devonian faunas in any region where con- 
tinuous sections have enabled the geologists to determine ac- 
curately their sequence. March 9, 1889. 
PRELIMINARY DESCRIPTION OF NEW LOWER SILURIAN 
SPONGES. 
By E. O. Ulrich. 
This paper may well begin with an apology for the scanti- 
ness of the descriptions and the lack of sufficient illustrations. 
It is hoped, however, that the critic will be lenient and bear in 
