IN THE LOWER CARBONIFEROUS OF SCOTLAND. 



35 



different corals from those to which he intended to apply it, 

 namely the fasciculate Lithostrontionts. Nevertheless, M. de 

 Koninck's reading of Lonsdale's definition of Diphyphyllum (pp. tit. 

 p. 33) does not satisfy those who believe in the fissiparity of the 

 individuals of its species. This is to be regretted, because it is now 

 shown by the Scottish specimens that Lonsdale was correct ; and, 

 moreover, in order to complicate matters, there are also forms in 

 the Scottish Carboniferous which agree with De Koninck' s insufficient 

 generic diagnosis, and which may be termed Lonsdale's Diphyphylla, 

 increasing by gemmation only, and with more or less united coral- 

 lites (see the concluding sentence of this communication). 



The specimen of Diphyphyllum concinnum, Lonsd., figured by De 

 Koninck does not show fissiparity ; but similar slabs are to be 

 obtained in the Scottish Lower Carboniferous, and fissiparity is 

 seen now and then in them, the greater part of the increase being due 

 to gemmation. De Koninck also considers H'Coy's D. latiseptatum 

 to be synonymous with D. continuum, the difference being due to 

 vigorous growth of the first-named coral. 



Lindstrom, in his useful index to the generic names of the corals of 

 Palaeozoic formations (Bihang till k. Svenska Yet.-Akad. Handl. 

 Bd. 8, no. 9, 1883), states that Diphyphyllum, Lonsdale, 1845, has 

 Eridophyllum, Ed. & H., as a synonym. This is an error, for Erido- 

 pliyllum differs very decidedly ; it does not increase by fissiparity 

 and has rootlets. 



The presence of several forms which must come within the genus 

 Diphy phyllum, Lonsd., in the Lower Carboniferous strata of Scotland 

 is placed beyond a doubt, and the difficulty is to distinguish species 

 from varieties. Certainly there are four groups of species and some 

 varieties which have been collected, and they may be divided as 

 follows : — 



1. The D. continuum group, with numerous primary and smaller 

 septa, not less than from 45 to 60 in number ; endotheca moderate. 



2. Large forms with long and shorter septa, about 40 in number ; 

 endotheca in two distinct circles, A new species, D. cylindricum, 

 comes in here, with a second, D. Blackwoodi. 



3. Large forms with numerous septa and much endotheca, filling 

 largely the interseptal loculi. Here come in D. latiseptatum, M'Coy, 

 and two varieties, var. giganteum and var. interruptum. 



4. Small forms with small corallites with few septa : D. gracile, 

 M'Coy. 



The following old and new species and varieties of the genus 

 Diphy phyllum, Lonsd., occur in the Lower Carboniferous of Scot- 

 land : — 



DlPHTPHYLLUM CONCTNNTIM, Lonsd. (PI. IV. fig. 1.) 



A variety with smaller corallites than the type, and about 44 septa ; 

 diameter 6 millim. by 8 millim., in the instance of the largest coral- 

 lites. The distribution of the endotheca, tabulse. and acicular points 

 is as in the type, and everything is on a smaller scale. The corallites 

 are tall and wide apart. Gemmation appears to be more frequent 



d 2 



