yh) REPORT— 1868. 
Davidsonia (Middle Devonian), Stringocephalus (Middle Devonian), Rensseleria 
(Middle Devonian), Zerebrirostra (Upper Greensand), Magas (Chalk). Thirty 
genera are essentially Paleozoic, and eight genera have not been found in any 
other than Mesozoic strata, though four of these have living representatives, while 
not one genus can be considered characteristic of Cainozoic strata. 
Of the nine families in which the forty-seven genera and subgenera may be 
placed, one, Productide, is confined to Paleozoic strata, and one, Thecidide, is 
characteristic of Mesozoic rocks, This family, however, although not represented 
in Cainozoic straia, has a species living in the present seas. Strophomenide and 
Spiriferde may almost be said to be Palzozoic, since very few species of either 
of these families have been found in rocks newer than the Permian, while in older 
strata the species of both are most numerous. 
The families which range from the Paleozoic rocks to the present time, and are 
represented by recent species, are Lingulide, Discinide, Craniade, Rhynchonellide, 
and Terebratulide. 
When we consider the range and distribution of the class as a whole, we find 
that it is represented in British strata by a very large number of species, some of 
which are found in almost cvery geological formation. Coming into existence, as 
far as we yet know, in Cambrian times, Brachiopoda abounded in Silurian seas ; 
but the class atta‘ned its maximum development in the Carboniferous period. A 
small number of species haye been taken from Permian rocks; but Triassic strata 
haye not hitherto yielded us any. When we examine Liassic and Oolitic strata, 
we find again a large number of species, which, however, become fewer as we 
ascend the scale until we reach the Portland rocks, in which no Brachiopod has 
been found. The class again increases in importance in Cretaceous strata, and 
again diminishes in Tertiary formations, which haye yielded hitherto not more than 
eight or nine species. ; ; 
Although in British seas living Brachiopeds are very rare, yet they are by no 
means so in the seas of southern latitudes, the bays and harbours of Australia 
swarming with Waldheimia and other forms of this interesting and remarkable 
class of the animal kingdom. 
On the occurrence of Spherical Iron Nodules in the Lower Greensand. 
By Joun Lown, M.D. 
Two years ago a large number of spherical pieces of sandstone was found in a 
railway-cutting at Walferton, near Lynn. They were mostly about the size of 
ordinary marbles, and were found to consist of a variable number of concentric 
laminge resembling the ordinary “car’-stone of the district, and containing in 
their interior a quantity of loose grains of pure sand, with occasionally a small 
vitreous-looking fragment of organic matter. 
The hill through which the cutting is made is about 50 feet in height at its 
highest point, and is composed of bands of yellow sand of variable degrees of hard- 
ness, but always of a friable nature. On the summit is a thin layer of iron or car- 
stone, which is largely used for building, There is no superincumbent chalk 
nearer than Sandringham, a distance of about a mile and a half. 
On examining the sides of the cutting, the sand was found to be perforated by 
some boring animal (a Jarge species of Zeredo? or Pholas?). The eee have 
generally a horizontal direction, but sometimes pass upwards from one layer of 
sand into another. They are usually long and somewhat widely separate, never 
apparently crossing each other, as is seen in Pholas-borings. They are filled with 
sand of a much coarser quality than that which surrounds them, but when they 
take an upward direction the sand they contain is of a finer grain. The periphery 
of the borings is hardened by the deposition of iron, so as to form a tube. At the 
extremity of each there occurs one of the spherical bodies above described. 
It is obvious that all the borings have been filled with sand, carried in and 
deposited by water, and that a stream of ferruginous water has subsequently per- 
colated through the bed of sand, giving rise at the same time to the nodules and 
to the hardened periphery of the tubes. ; 
It seems not improbable that the deposition of the iron has been determined by 
a 
