IX THE LOWER CARBONIFEROUS OF SCOTLAND. 



37 



Locality. Boghead, Lesmahago ; Eoughwood and Thirdpart, Beith, 

 Ayrshire. 



DlPHTPHTLLFM LATISEPTATTJII, M'Coy. (PI. Y. fig. 6.) 



This form must now he separated from D. concinnum, for the 

 specimens show a large corallite with 52 septa in all, longer primary 

 septa than in D. concinnum, and a very considerable vesicular 

 endotheca filling the interseptal loculi, and much more of it than in 

 the species determined by Lonsdale. Both kinds of fissiparity are 

 present. 



Localities. Corrieburn, Dumbarton, and Eenwick, Ayrshire. 

 There are two varieties of this species, var. giganUum (PI. Y. 

 figs. 7 and 8) and var. interruptum (PI. Y. fig. 9). 



DlPHTPHTLLTOI GBACLLE, lE'Coy. (PI. Y, fig. 10.) 



This is the smallest species of the genus, and the Scottish 

 specimens are fairly undistinguishable from the type. The septal 

 number is small, and there is fissiparity as well as gemmation to be 

 observed in the method of increase of the individuals. The corallites 

 are in tortuous, ascending, and irregular bifurcating masses. 



Localities. Cotcastle near Strathaven ; Braidwood and Brockley, 

 Lesmahagow : Eoughwood and Cunningham, Bedland Dairy, Ayr- 

 shire. 



List of Scottish Lower Carboniferous Species and Varieties 

 of Diphyphyllurri, Lomcl. 



1. Diphyphyllum concinnum, Lonsd., variety. 



,, var. furcatum. 



2. „ Blackwoodi, sp. nov., and var. appro xinwtum. 



3. „ cylindricum, sp. nov. 



4. „ latiseptatum. M'Coy, and vars. giganteum and interruptum. 



5. „ gracile, M'Coy. 



Some of these forms are found in large masses and environed and 

 covered by volcanic ash. It is not too much to believe that some 

 of the variability of the species may have been produced by the 

 rather frequent slight changes of external conditions which must 

 have accompanied the vuleanicity of the Lower Carboniferous age. 

 Indeed, the volcanic ejectamenta appear to have finally destroyed 

 the life of the individuals over the area, for the species are not 

 found in a higher geological horizon. 



The examination of the numerous species and varieties of the 

 genus established by Lonsdale enables the truth of his description 

 and diagnosis to be appreciated. His only mistake was an omission; 

 for when he stated that the species increased fissiparously, he did 

 not also state, what has been shown here, that gemmation also 

 occurs. The description given of the tabulae by Lonsdale is correct, 

 and so is that of the acicular points sometimes becoming rods which 

 do not extend for any great height in the centre of the corallum. These 



