1885.] ` Geology and Paleontology. 707 
Cambrian.—Mr. Chas. D. Walcott (Amer.. Your. of Science, 
April, 1885) describes Mesonacis, a new genus of Cambrian trilo- 
bites, intermediate between Paradoxides and Olenellus, the head 
and first fourteen segments being of the type of the latter, while 
the pygidium and ten posterior segments more resemble the 
former. The fifteenth segment fits snugly against the fourteenth, 
and has a long, slender spine extending to the pygidium. Meso- 
nacis vermontana occurs in the Georgian of the State it is named 
after. 
Carboniferous—MM. Renault and Zeiller have described a 
number of mosses from the carboniferous strata of Commentry 
(France). The mosses previously found in a fossil state have been 
few, and of the Tertiary epoch, principally Miocene, but the Com- ` 
mentry beds contain many impressions of their stems, three or 
four centimeters long, some simple, others with alternate fronds. 
The stems are usually united in tufts. The absence of any trace 
of the organs of fructification prevents the determination of the 
place of these fossils in present classifications, but MM. Renault 
and Zeiller think they belong rather among the acrocarps than 
among the pleurocarps. and J. W. Kirkby give, 
in the Ann. and Mag. of Nat. Hist. for March, a synopsis of the 
species of the ostracodous genus Kirkbya, eleven in number. 
Most of the specimens are from marine shales associated with the 
calcareous beds of the Carboniferous series. 
Tertiary.— Mr. J. W. Judd has shown that in the Western isles 
of Scotland there occur a number of peridotite rocks which are 
the central cones of Tertiary volcanoes of vast dimensions. These 
Tertiary peridotites are intimately associated with the gabbros and 
dolerites, and present numerous variations both in structure and 
mineralogical constitution. Among them occur examples of the 
rocks which have received the names of dunite, picrite and lher- 
zolite. Dr. C. J. Forsyth Major (Quart. ‘Jour. Geol. Soc., 
1885) gives a list of thirty-nine species of fossil Mammalia found 
in the Val d’Arno. Not one of the members of the rich fauna 
found in the Mediterranean region and as far east as the Siwaliks 
of India, and existing on the boundary line between the Miocene 
and Pliocene, is found in the Val d’Arno, though the two ante- 
send the Machairodus and the Mastodon, are closely allied. 
s Mediterranean fauna occurs at Casino, near Siena, and the 
kaviat T e Hons of the Val d’Arno was also spread as 
far as India. The shore deposits of the Pliocene sea in Italy are 
said by Dr. Major to contain the same mammalian fauna as the 
lacustrine deposits of the Val d’Arno. The Post-pliocene fauna 
exhibits several connecting links with the Pliocene, oe Bg Italy 
“at least, not a single species of the older fauna seems to have 
gone over, as such, to the younger fauna. Nota le acer 
of the thirty- nine is identical with those living to-day, and five 
