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Transactions of the Society. 
according to age of these small divisions of the strata, the ruling factor 
in the distribution being probably the existing conditions under which 
the bed was deposited ; and therefore we find a nearly similar repetition 
of the facies when the same lithological aspect recurs. 
Miliolina venusta Karrer sp. is by far the commonest species of the 
porcellanous group occurring in the Gault of Folkestone, and is found 
consecutively from zone x. up to the top of zone xiii. at 6 ft. below the 
Chloritic marl. 
The Family of the Astrorhizidse. The only representative is Astro - 
rhiza indivisa Brady, and the solitary specimen occurred in zone xi. at 
the level of 50 ft. from the top. The incoherent nature of the tests of 
many of these forms possibly explains their general absence from the 
older fossiliferous strata. 
The Family of the Lituolidse. The genus Reophax appears to bo 
restricted to the Upper Gault, and especially favours zone x. The genus 
Haplophragmium is a ubiquitous one in the Gault, and many of the 
species recorded are well distributed throughout. Some other genera, as 
Placopsilina, Haplostiche, Thurammina , Hormosina , and Trochammina , 
are of very occasional occurrence ; but Ammodiscus i represented by four 
species, is commonly met with above zone ii. 
The Family of the Textulariidse. The genus Textularia comprises, 
some species, as T. minuta Berthelin, T. sagittula Defr., T. trochus d’Orb., 
and T. complanata Reuss sp., which are found scattered irregularly 
through the Gault ; whilst a few others, as T. gramen d’Orb., T. conica 
d’Orb., T. agglutinans d’Orb., T. parallela Reuss, and T. prselonga Reuss, 
range through zones xi., xii., and xiii. It is also worth noting that 
whilst T. agglutinans is found at three levels only, in zones xi. and xii., 
another form easily to be confounded with it, but having a triserial com- 
mencement, namely Gaudryina pupoides d’Orb., has a range extending 
throughout the thirteen zones ot the Gault, in some of which, unlike 
T. agglutinans , it is very common. The genera Tritaxia, Spiroplecta, 
and Bulimina begin to make an appearance in zone v. and continue to 
the top of the Gault. Of the Buliminse it is interesting to notice that 
B. Presli Reuss, which is perhaps the most characteristic of the Gault 
species of the genus, begins at zone v., and continues more or less com- 
mon up to the topmost level ; and it is accompanied in the last three 
levels of zones xii. and xiii. (12 ft. and 6 ft. down) by a coarsely arena- 
ceous variety named sabulosa. The single species of Bolivina , B. texiu - 
larioides Reuss, is found commonly throughout the Gault. 
The Family of the Lagenidse. This comprises by far the largest 
number of the Gault Foraminifera. The genus Lagena is well represented ; 
but with the exception of L. apiculata Reuss, and L. hispida Reuss, they 
are altogether rare. The genus Nodosaria , in common with Cristellaria , 
comprehends the largest number of species and varieties in any one genus 
of the Gault Foraminifera. The most abundant forms of this genus are 
N. (Z>.) communis d’Orb., N. prismatica Reuss, and N. orthopleura Reuss.. 
It is strikingly shown in this genus that there are many more of the Gault 
species peculiar to the Upper Gault, and further, generally passing into 
the Chalk above, than there are peculiar to the Lower Gault, and passing 
downwards. This significant fact was shown by Dr. Reuss in his work 
