HALLE, ON THE SPORANGIA OP SOME MESOZOIC PERNS. 3 



presenting habitual resemblance to Marattia. Both Seward 

 (1. c.) and Thomas (1913, p. 228) have used Marattiopsis 

 for forms with typical Marattia-sjnangiai, and for the present 

 it would seem to be best to follow this course. I propose, 

 however, to restrict the use of the name Marattiopsis to forms 

 which, in synangial characters or in other respects, agree 

 closely with the recent genus. 



In the species known as Danaeopsis marantacea, the 

 structure of the sorus is now well known, and is found to dif- 

 fer markedly from that of Marattia. Forms having the soral 

 characters of Danaeopsis marantacea ought therefore to be 

 kept under a separate generic name. 



Krasser (cf. above, p. 2) has stated that the name 

 Danaeopsis, as used for these species, is not valid because of 

 the previous existence of Danaeop^s Presl. This latter 

 name, however, is itself not a valid generic name and its exist- 

 ence, therefore, according to present rules of nomenclature, 

 does not constitute a sufficient ground for rejecting Danae- 

 opsis Hr. The substitution of Pseudodanaeopsis Font, for 

 Danaeopsis Hr. is accordingly not warranted, according to 

 the rules of priority, besides being in other respects undesir- 

 able. 



It may be questioned whether the genus should not on 

 strict grounds of priority be called Marantoidea, as the er- 

 roneous suggestion of a relationship with Maranta is not ac- 

 cepted as a sufficient ground for rejecting an earlier name. 

 Heer, however, instituted his genus for a plant with a peculiar 

 type of fructification while Marantoidea was used for a sterile 

 fragment of a pinna which has not been proved to have a 

 similar fructification. Although there is not much doubt that 

 Jaeger's Marantoidea arenacea was really a sterile pinna of 

 Danaeopsis marantacea, it seems to be better to regard this 

 identity as not quite settled and therefore to retain Heer's 

 genus. The name Danaeopsis it is true, is not very fortunate, 

 since it suggests a resemblance to Danaea while the genus 

 agrees much more closely with other recent genera of the 

 Marattiaceae. 



The structure of the sori and the sporangia of Danae- 

 opsis marantacea has been differently interpreted. Schenk 

 (1859, p. 191; pi. 4, figs. 1—3), who is the first to have de- 

 scribed a fertile specimen, refers the species to the genus Thau- 



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