102 THE ROYAL SOCIETY OF CANADA 



Devonian rocks of Ireland is A. Romeriana Gopp, distinguished by 

 its more upright pinnae and small, stalked pinnules. 



We seem then to have the following forms of Archaeopteris 

 from the Devonian rocks of Ireland: 



\. A. hibernica described by E. Forbes. 



2. A. h. var. minor, Crepin. 



3. A. h. var. geniculata n. var. 



4. A. romeriana, Gopp. cited by Pf. Johnson. 



5. A. Tschermaki, Stur, cited by Pf. Johnson. 



CYCLOSTIGMA. 



"A new genus of Fossil Plants from the Old Red Sandstone of 

 Kiltorcan," etc., By Rev. (Prof.) Samuel Haughton. Read at Royal 

 Dublin Society, May, 1859." 



This form has of late years been referred to the genus Bothroden- 

 dron of Lindley and Hutton, but it seems to the writer not with 

 sufficient justification. Bothrodendron, a genus of the Coal Measures, 

 was a fossil characterized by a vertical series of large, deep pits or 

 scars arranged along the side of the trunk. It is true that Lindley 

 and Hutton noticed "a considerable number of minute dots arranged 

 in a quinouncial manner, w'hich he thought might probably be scars 

 of leaves." 



Later geologists have confirmed this conclusion, but no emphasis 

 seems to have been put on the peculiar arrangement of these leaf-scar 

 bases in transverse rows in Cyclostigma which both Houghton and 

 Johnson emphasize in text and figures, and which does not seem to be 

 notable in the original Bothrodendron of Lindley and Hutton. The 

 writer has handled a number of the fossil plants of Devonian age 

 referred to Bothrodendron, but on none has he found the deep, large 

 Ulodendroid scars characteristic of the original Bothrodendron of 

 the Coal Measures, and from which it seems to have derived its generic 

 name. 



Prof. Samuel Haughton after an introduction devoted to the laws 

 of phyllotaxis found to hold in several of the leading genera of plants, 

 says: "The leaves (or leaf scars) are arranged in whorls so placed 

 that each leaf is directly above or below a leaf of the alternate whorls, 

 and intermediate to the leaves of the adjacent whorls. These leaves 

 are developed in simultaneous whorls, and not produced in succession 

 as in alternate-leaved [modern] plants. 



"It is worthy of remark that the w^horled arrangement of the 

 leaves among the coal plants, holds so far as we know, among the 

 plants of the Old Red Sandstone, which forms the base of the Carbonif- 

 erous rocks; these also produce simultaneous whorls. 



