46 ONYCHIOPSIS. 
pteris described in the following pages show a good many features 
similar to those of Sphenopteris Mantelli, as described by Schenk 
and Heer.” In his description of Z. 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 Zhyrsopteris 
type.” Again, in describing Z. insignis and TZ. insignis, var. 
angustipennis, the same author adds that both represent plants 
belonging to the S. Mantelli type.2 From an examination of 
Fontaine’s figures of the various species of Zhyrsopteris, it is 
difficult in some cases to thoroughly appreciate those characteristics 
which have served to separate the closely allied forms. 
In discussing ‘‘S. DMantelli,’’ Fontaine refers to its polymorphous 
nature, and prefers to include several plants of the Jantelli 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 TZhyrsopteris and O, Mantelli. 
The figures of Z'hyrsopteris insignis*® show a striking resemblance 
to O. Mantelli, but in the larger specimens there appears a certain 
difference 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 O. 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. 
2 Thid. p. 128. 
8 Ibid. pl. xiii. figs. 1-3. 
4 Ibid. pl. xlii. fig. 3; pl. xiii. fig. 2. 
5 Abh. k. bohm. Ges. Wiss. vol. ii. 1888, p. 10. 
§ Loe. cit. p. 55. 
