Dr. H. Woodward—Carboniferous L. Trilobites. 440 
power of the sea and of little but the sea. And we all recognize in 
geology a tendency to the excessive invocation of an agency which 
like that of rain and rivers, or glacial action, has become potent to 
explain much that before its rise seemed almost beyond explanation. 
But this tendency, like all tendencies to excess, requires guarding 
against. ‘The Peruvian testimony on the subject of eskers may 
therefore be valuable in other ways than that of showing conclusively 
_ the power of the sea alone to form these strange ridges, unaided by 
either rain or rivers. Tor it is possible that there may now be some 
danger of unjustly disparaging the powers of the sea, just as some 
years ago there was a tendency to a le exaggeration of their 
influences. 
LV.—Svvorsts or THE GENERA AND SPECIES OF CARBONIFEROUS 
Limestone TRILOBITES. 
By Henry Woopwarp, LL.D., F.R.S., F.G.S. 
(PLATE XI.) 
AVING published in the Palzeontographical Society’s Volume 
for the current year the first part of my Monograph on the 
Trilobites of the Carboniferous Limestone, it occurred to me that a 
brief account of the species described might prove useful to some of 
the readers of the GronocicaL MaGazine. 
I have prefixed a note on a pygidium of a new Trilobite which 
has since come under my notice, which I believe belongs to the 
genus Proetus. Should any of my readers possess new and un- 
described forms of Carboniferous Trilobites, they will greatly oblige 
me by placing them in my hands to be figured and described in the 
second part of my Monograph. 
J intend also to give a list of all the species of Carboniferous 
Trilobites hitherto described, both British and Foreign. 
The Family Proetide was originally proposed by the late Mr. 
J. W. Salter (Pal. Soc. Mon. 1864, p. 2) to comprise the four genera 
Proetus, Phillipsia, Griffithides and Brachymetopus. The first-named 
genus had not until lately been recognized from the Carboniferous 
Limestone, but the three latter genera have only been found in that 
formation. 
M. Barrande has suggested that Dr. Sandberger’s genera Trigon- 
aspis and Cylindraspis, from the Devonian of Nassau, also belong to 
the genus Proetus. Prof. Dr. Ferd. Roemer has also figured and 
described four species of Proetus from the Harz, and Messrs. Meek 
and Worthen have named a species of Proetus from the Lower Carbon- 
iferous series of Jersey Co., Illinois, so that Proetus seems to have a 
much wider range than the other genera, and serves to connect the 
otherwise detached group of Mountain Limestone forms with their 
relatives in the Devonian and Silurian formations. 
J.—Proetvs, Steininger, 1830.—The general form of the body is 
oval; the trilobation very distinct, through the entire length of 
body ; the head-is less than a third of the total length ; the pygidium 
is rather longer than the head ; the head-shield is always surrounded 
by a border consisting of an exterior raised rim and an inner groove 
