FROM THE ZONE OE AMMONITES ANGULATUS. 



35 



The range in space and in time of some of these species is veiy remarkable. Several 

 of them range from the Italian to the Welsh Lias, and from the Zone of Avicula coiitorta 

 to that of Ammonites BucHandi; but the general grouping of the Gasteropoda, Lamelli- 

 branchiata, and Madreporaria indicates a Zoological Province which flourished anterior 

 to the characteristic fauna of the time of Gryphaa incurva and Ammonites BucUandi} 



The richness of the Glamorganshire beds beneath the arenaceous deposits containing 

 Gryphcea incurva in species and specimens is very evident. The Madreporaria are rare in 

 the equivalent strata on the Continent. 



IV. Description- of the Species from the Zone of Ammonites Angulatus at 

 Marton, near Gainsborough. 



At Marton,^ on the line of railway from Gainsborough, in Lincolnshire, to Lincoln, 

 there are dull blue earthy and shelly limestones, which are very fossiliferous. These beds 

 have been carefully searched for fossils, and a very rich and interesting fauna has been 

 collected.^ 



They occupy a position above the White Lias and below the blue compact limestones 

 of the Ammonites BucUandi series. 



The fauna is very characteristic, but the Madreporaria are allied rather to those of 

 the equivalent beds of the Lower Lias in the North of Ireland and of the East of Erance 

 than to the species at Brocastle and in the Sutton Stone. 



1. Montlivaltia Haimei, Chapuis et Bewalque. PI. X, figs. 24 — 32. 



" The corallum is simple, discoidal, and depressed ; the base is very slightly pedicillate ; 

 the epitheca is very thin, ridged, and extends to the calicular margin. 



"The calice is circular in outline, slightly or not at all convex, and the central fossa is 

 small and circular. 



" The septa are numerous, and form six cycles in six systems. The primary and 

 secondary septa nearly reach the centre of the calice, and barely difier from those of the 

 third cycle. The septa of the sixth cycle are very small. All the septa are thin, and 

 their margin is strongly crenulate ; those of the first and second cycles become thicker 

 near the centre of the calice, and thinner at the periphery, where all the septa are about 

 the same thickness." ('Descript. des Eoss. desTerr. Second, du Luxembourg,' Chapuis et 

 Dewalque, p. 268.) 



The resemblance of the species to a Cyclolite is noticed by M^I. Chapuis and 



1 P. Martin Duncan, 'Quart. Jour. Geol. Soc.,' Feb., 1867. 



2 r. M. Burton, Esq. ,F.G.S., and the Rev. B.Chamberlin, E.G. S., have given me information on this section. 

 5 Ralph Tate, Esq., F.G.S., " On the Fossiliferous Development of the Zone of ^. angulatus, &c.," an 



unpublished paper from which I have obtained much information, and all my knowledge of the Molluscan 

 fauna of Marten. 



