R. G. Carruthers — A Revision of some Carboniferous Corals. 169 



Amplexus coralloides, Sow., differs in the possession of a very 

 inconspicuous cardinal f ossula, no dissepimental margin, and an absence 

 of a dumonti phase. 



Amplexus cornuformis, Ludw., may present resemblances in trans- 

 verse section, but the tabulee (if de Koninck is correct in assigning to 

 Amplexus cornuformis the tabular sections given on pi. ii, figs. \c 

 and Id, of Milne-Edwards & Haime's " Polypes Fossiles ") are more 

 irregular and vesicular than in Caninia conmcopia}. 



Corals, as yet undescribed, of a very similar nature to Caninia 

 cornucopice, are found in the Yisean, and many of these are certainly 

 congeneric. Through the kindness of Mr. Sibly, I have been able to 

 examine several of these from the shales overlying the Derbyshire 

 Limestone. But none of them seem quite identical with Michelin's 

 species, and the majority show well-developed minor septa, and, as far 

 as one can judge from transverse sections, they appear to have highly 

 vesicular tabulae. Other closely related forms are also present in the 

 Visean of the South- West Province, and concerning these Dr. Yaughan 

 lias kindly drawn up the following notes, where the differences from 

 typical examples of C. cornucopim are clearly set forth. 



" Caninia aff. cornucopice, mut. D3_3, agrees very closely with the 

 Tournaisian species. 



"The following differences are, however, constant in the specimens 

 which I have specially studied, i.e., of the Tournaisian species from 

 IS". Mendips and Stackpole Quany (Pembroke) and of the Visean 

 mutation from Oystermouth (Gower) and the Hodder : — 



" The Tournaisian species is curved almost throughout its length, 

 whereas the Visean mutation adopts a cylindrical habit at an early 

 stage. Apparently connected with this habit of growth is the per- 

 sistence of the thin vesicular jacket throughout the cylindrical stage 

 of the Do_3 mutation and its very brief development in the Z-C species. 



"The most striking differences seen in a comparison of a set of 

 serial slices are (1) the deep siphuncular depression of the tabulae 

 in the case of the Tournaisian form, and the broad, relatively shallow 

 depression in the case of the Visean mutation ; the lower form may 

 therefore be stated to have a Caninoid and the upper a Campophyllid 

 type of fossula. (2) The greater abundance of tabular intersections 

 between the septa in a horizontal section of the upper form, pointing 

 to the closer approximation of the tabulge, a fact which is confirmed 

 directly by comparing vertical sections." 



Another mutational form is locally extremely abundant in 

 Scotland, on the horizon of the Middle Skateraw Limestone, especially 

 in the shales overlying that limestone in the East Barns Quarry near 

 Dunbar. 



This form differs from the Tournaisian species in having more 

 widely spaced septa, and, like the mutation described above by 

 Dr. Vaughan, a comparatively slight depression of the tabulse into the 

 cardinal fossula, but in other respects the resemblance is extremely 

 close. It is interesting to note that the remarkable variation in 

 habits of growth, seen in the Tournaisian species, also occurs here. 

 The simple conical form is by far the commonest, as it is with the 

 original species at Tournai and in the Bristol area. 



