118 Scientific Proceedings, Royal Dublin Society. 



doubt in my mind that the true position of A. liibernica is in tlie Marat- 

 tiacese." 



In 1894 Schmalhausen (18) described two new fertile species' of 

 ArchEeopteris from the Upper Devonian deposits of Donetz-Becken in 

 South Eussia — A. archetyfm and A. flssilis.. 



One species, A. archetypus, occurs in the lower strata in this fossil locality. 

 Its nearest affinities are stated to be A. Gaspiensis, Dawson, and A. hibernica, 

 Forbes sp. Its pinnules are described as spirally arranged— a remark which 

 is applied to the fertile pinnules too. One or two of the figures seem to 

 support the view of the spiral arrangement, but in specimens of tlio same species 

 subsequently described by Nathorst (19) from Ellesmero Land, as well as 

 in Sohmalhausen's own type specimens, the spiral character is not observable 

 by Natliorst. I have seen in specimens of A. hihernica fertile pinnae in 

 which the pinnules appear arranged just as in Sohmalhausen's figure of 

 A. archetypus (op. cit., Taf. 2, fig. 19), and I am satisfied there is no spiral 

 arrangement of the pinnules in A. hihernicri. The ordinary pinnee and pinnules 

 in A. hiberiiica are readily recognizable as two-ranked or distichous ; and if the 

 fertile pinniiles are not always visible their whole length in the stone, their 

 points of insertion are so, generally, and they show that the pinnules are not 

 spirally or radially arranged. Involved in the interpretation of the mode of 

 arrangement of the pinnules is the question of tlie morphological nature of 

 the various structures. If the frond of A. archetypus, wliether sterile or 

 fertile, presented a spiral arrangement of its parts, it would differ in this 

 respect from every living or extinct fern or fern-like frond, and would 

 thus show itself more stem-like and more primitive (?) than any other 

 known frond. Further, it would be necessary to raise A. ai-chetypus to 

 generic rank, and to separate it from the two species A. hibernica and 

 A. Gaspiensis, from which, except for its alleged spirality, it would be other- 

 wise scarcely distinguishable. Its pinnules are described as more wedge- 

 shaped below and rounded above than those of A. hibernica, being more like 

 those of A. Gaspioisis. (The variety of form of the pinnule observable in true 

 A. hibernica specimens makes me attach less systematic value to the form of 

 the pinnules.) Some pinnules are described as the same size as those of 

 A. Roeineriana ; others are as large as those of A. obtusa [C. oblusa, Lesqx.), 

 and others of average size, like those of A. hibernica and A. Gaspiensis. 



' I have not yet been able to see the evidence on which Dr. "White bases the following 

 statement : — 



'^ Arehteopteris oblusa axiA. Archaopteris sphenophijUifolia of Pennsylvania and New York are 

 A. archetypus and A.Jissilis of EUesmere Land, Spitzbergen, and the Don." D. White : The Upper 

 Palaeozoic floras, their Succession and Eange, p. 142, in "Willis and Salisbury's " Outlines of Geologic 

 History, with special reference to North America." — Chicago, 1910. 



