chief Oeneric Types of Palceo zoic Gonds. 80/3 



again, as described and figured by Mihie-Edwards and Haime, 

 appears to differ in no essential structural character from 

 Lonsdaleia, from which it is separable chiefly by its being 

 simple instead of compound. If this identity of structiu'e 

 should be confirmed by further investigation, it will become 

 very doubtful if the genus AxojdiyUum can be retained ; but 

 we have at present no sufficient means of arriving at a final 

 judgment on this point. From the description given by Prof, 

 de Koninck, on the other hand (An. Foss. Nouv. Recherches, 

 p. 23), it would seem that the septa of Axophyllum are in con- 

 nexion with the outer wall, which would constitute a sufficient 

 distinction from Lonsdaleia. Another ally of Lonsdaleia, in a 

 somewhat unexpected quarter, is found in the genus Clisio- 

 phyllum, Dana. Both these genera have a distinct columel- 

 lary line, and possess a few lamellge, which spring from near . 

 the inner margins of the primary septa, and are connected by 

 a system of endothecal dissepiments. On the other hand, 

 Lonsdaleia is distinguished from Clisiophyllum hj being com- 

 pound, by increasing by calicular gemmation, by the fact that 

 the septa are not connected with the external wall, and by 

 the large size of the vesicles of the exterior vesicular zone. 

 Finally, the genus Koninckophyllum, Thoms. & Nich., is 

 distinguished from Lonsdaleia by the fact that the septa are 

 directly connected with the outer wall, by the different nature 

 of the columella, and by the minute and dense vesicular tissue 

 of the outer zone, as well as by the generally simple nature of 

 the corallum. 



In its range the genus Lonsdaleia is restricted, not having 

 been hitherto found to transcend the limits of the Carboniferous 

 rocks. 



EXPLANATION OF THE PLATES. 



(Unless otlien\'ise stated, the figures are of the natural size.) 



Plate XII. 



Fig. 1. KoninckophyUum prolifernm, Thomson and Nicholson, transverse 

 section of a small slab exhibiting the different stages of growth 

 by calicular gemmation. Lower Carboniferous, Bathgate, Lin- 

 lithgow^shire. 



Fig. 2. KoninckophylUitn magni/icHm, Tlionisoii and Nicholson, transverse 

 section of an exceptionally large example ; 2 a, longitudinal sec- 

 tion of the same, exhibiting the columellary line, the large 

 tabulate area, and the dense outer vesicular zone. Lower Car- 

 boniferous, Charleston, Fifeshire. 



Fig. 3. Transverse section of Koiiinckojjhylhdn interrnptum, Thoms. and 

 Nich. The section is cut about a quarter of an inch below the 

 floor of the calice, and does not show any signs of the columella, 

 proving that this organ is really absent occasionally in portions 

 of the corallum : the septa also are seen to be wanting at 

 certain points : and these vacant spaces are the bases of young 



