46 OlfTCHIOPSIS. 



pteris described ia the following pages show a good many features 

 similar to those of Sphenopteris Mantelli, as described by Schenk 

 and Heer." In his description of T. rarinervis, Fontaine speaks 

 of his new species as ^ " one of the Sphenopteris Mantelli type, and 

 perhaps by some would be united with that species, but it is more 

 robust, and the pinnules are more like those of the Thyrsopteris 

 type." Again, in describing T. insignis and T. insignia, var. 

 angustipennis, the same author adds that both represent plants 

 belonging to the S. Mantelli type.' Prom an examination of 

 Fontaine's figures of the various species of Thyrsopteris, it is 

 difficult in some cases to thoroughly appreciate those characteristics 

 which have served to separate the closely allied forms. 



In discussing " S. Mantelli," Fontaine refers to its polymorphous 

 nature, and prefers to include several plants of the Mantelli type 

 under the genus Thyrsopteris. Except in cases where the fructi- 

 fication has been preserved it is questionable whether the better 

 course would not be to retain the old name, and not introduce new 

 ones without trustworthy evidence. Fortunately some of the 

 specimens recently acquired by the British Museum show distinct 

 fertile segments, and thus enable us to refer the species with some 

 degree of certainty to its living representative ; the character of 

 this fructification lends no support to the suggested relationship 

 between Thyrsopteris and 0. Mantelli. 



The figures of Thyrsopteris insignis ^ show a striking resemblance 

 to 0. Mantelli, but in the larger specimens there appears a certain 

 difierence of habit, and, in addition to this, Fontaine refers to some 

 other differences in detail. His figures of the variety angustipennis* 

 would at once be taken for 0. Mantelli, were it not that the rachis 

 is not winged and that other points of divergence are insisted on. 

 The same reference has been made by Velenovsky ^ to Thyrsopteris 

 in the case of ferns which must now be included under the genus 

 Onychiopsis. 



In a recent paper by Nathorst,* referred to in the list of 

 synonyms, we find the statement that Sphenopteris Mantelli will 



1 Potomac Flora, p. 123. 



" Ibid. p. 128. 



3 IHd. pi. xliii. figa. 1-3. 



< Ibid. pi. xlii. fig. 3 ; pi. xliii. fig. 2. 



6 Abh. k. bohm. Ges. Wiss. vol. ii. 1888, p. 10, 



' Zoc. cit. p. 55. 



