Rcvieiv of Recent Geological Literature. 193 
It is contained in what has been denominated the "Upper Cambrian" 
of Portugal as distinct from the '"Lower Cambrian," which M. Del- 
gado places on a par with the Algonkian, Huronian, Keweenawan, etc. 
The fauna is contained in a schistose group of beds immediately 
subordinate to a heavy body of limestones which he designates as the 
limestones of Villa Boim. The underlying beds are chiefly quartzytes 
100 metres thick. The fossils were taken from a thin layer of slate 
about a centimetre thick in the top of the quartzytes. Beneath the 
quartzytes above mentioned are other quartzytes, slates, etc., of great 
thickness, of the same series. 
The fossils were very irregularly distributed in the slates and were 
preserved in spathic iron which by its oxidation discolored the rock 
and revealed the position of the fossils. These are consequently moulds 
of the tests showing the outer and inner surfaces of the fossils. The 
greater part of them are the remains of the heads of trilobites ; the mov- 
able cheeks are usually wanting, and fragments of the thorax and 
pygidia are rare. The fauna is chiefly composed of species not hither- 
to known or described. Besides the trilobites there are several species 
of pteropods (Hyolithidre) lamellebranchs and brachiopods. 
The existence of several species of lamellibranchs in this fauna is 
worthy of attention ; they are of small size and carry genera described 
by Dr. Henry Hicks from the Tremadoc down to this horizon. 
There are innumerable detached heads and pygidia of trilobites of 
the genus Microdiscus imbedded with the other fossils. No example 
of an inroUed trilobite of any genus w-as found. 
Upon the varied forms referable to the genus Micro.'liscus M. Del- 
gado bases the opinion that this fauna is allied to that of Olenellus in 
America. 
However, if a comparison is made with the fauna of Wales studied 
by Hicks this Portuguese Cambrian fauna is best represented by the 
Solva group fauna of Wales. 
In the Siberian Cambrian fauna described by von Toll there are s* 
number of related forms especially in the genus Microdiscus. M. Del- 
gado considers that the Portuguese species showing relation with the 
Olenellus fauna are of greater importance than those which connect 
it with the Paradoxides fauna. 
Of Paradoxides five species were found, indicated either by a 
sufficiency of parts to determine the species, or by fragments. 
In this memoir M. Delgado elaborates the character of a new genus 
— Hicksia, founded on a group of species resembling Salter'':; species 
Conocoryphc Iiumerosa: it has the tumid cheeks and glabella of Solen- 
opleura with the smooth test of Liostracus. but the back of the glabella 
is narrower than in Liostracus ; like the latter it has a quite small py- 
gidium. No less than nine species referable to this genus are described. 
Of the genus Microdiscus five species are described. They are 
mostly smooth forms such as are found in the OlenJellus fauna: and 
faunas referred to that horizon. 
