Geological Society of London. 113 
In the Craniade, represented by the single genus Crania, | 
we have a type of Brachiopod almost equally present at all 
epochs. The nearly allied group of Discinide, though ex- 
tending to the present, is generically concentrated in the 
Lower Palzozoics. The same remark may be made re- 
spaniang the Lingulide. 
_ Accepting the genera adopted by Mr Davidson as shit 
ally equivalent groups, and regarding their distribution in 
time as determined by him for a vast amount of specific 
materials, enough to induce us to believe that future dis- 
coveries will not materially disturb any inferences drawn 
‘from the numbers as now presented to us, then we arrive at 
several striking conclusions concerning the entire sub-class. 
Regarding the Present and the Lower Paleozoic epochs as 
opposite poles of time, we find the generic types among the 
Brachiopoda concentrate as it were around or towards each, 
whilst they depauperate towards the equatorial region of 
the scheme, about which indeed no generic types originate. 
The loop-armed types are regnant, as it were, anteally, the 
spiral-armed types posteally ; and the latter are in the main 
so dominant, that the Brachiopoda, as a great assemblage of 
types, has its major development towards the past, its minor 
towards the present, and its zero in the parting aback be- 
tween the paleozoic and after-ages. 
One of the distinctive features of our science during the 
year just past, is the monograph of Nummulites by Vicomte 
_-d’Archiac, constituting a portion of the “ Description des 
_ Animaux Fossiles du Groupe Nummulitique de l’Inde.” 
The high geological value to which the Nummulites and 
their order, the Rhizopoda, have speedily attained during the 
last fifteen years, contrasts curiously with the degradation 
they have as rapidly undergone during the same period in 
zoological position. Before 1835, they were generally re- 
garded as Cephalopoda, and naturalists of repute were not 
- wanting who went so far as to describe even the parts of the 
- minute cephalopod that constructed the foraminiferous shell. 
That they were not Mollusca was scarcely suspected, though 
_ half a century before their lower nature had been, on slender 
grounds however, often maintained. The assumption of their 
VOL. LVII. NO. CXIII.— JULY 1854. H 
