94 prof. a. c. sewaed: coxteibtjtiox to [March 19 13,. 



large number of closely-packed sporangia; but, just as in the 

 Sussex specimens, there is no evidence as to the nature of the 

 sporangia. 



A specimen figured by Fontaine as Baieropsis pluripartita l bears- 

 small oval bodies, regarded by the American author as seeds, which 

 bear a fairly close resemblance to the spore-masses of Pelletieria. 

 Fontaine's species is included by Berry 2 in the genus Acro- 

 stichopteris. 



A fragment figured by Saporta from the Lower Cretaceous beds 

 of Portugal as Pteridoleima spoliatum 3 is not unlike the fossil 

 represented in text-fig. 3B (p. 92). Fertile specimens of the 

 Cretaceous species Onodea inquirenda Xfoll.* may be compared 

 with the English specimen, but the habit is distinct. 



Dr. Stopes & Dr. Fujii 5 have described a specimen from the Upper 

 Cretaceous rocks of Northern Japan under the name of ScJiizceopteris 

 mesozoica, which in the occurrence of sporangia in groups suggests 

 comparison with the Wealden species. In the Japanese type the 

 sporangia are preserved ; whereas in Pelletieria there is no indication 

 of individual sporangia within the enclosing membrane. 



The habit of Pelletieria reminds one of the fertile pinnae of Thvr- 

 sopteris elegans, with the cup -shaped indusia and protruding groups 

 of sporangia like miniature bunches of grapes ; but in Thyrsopteris 

 the spores are smooth, and in Pelletieria there is no indication of 

 any cup-shaped indusium. The fertile portions of some Botrychium 

 fronds present a certain resemblance to those of the Wealden fern, 

 but the spores have no surface-ridges. 



Some of the fertile pinna? of Jurassic ferns from Cracow, figured 

 by Raciborski 8 as species of Diclsonia (more fittingly named 

 Coniopteris), are of the Thyrsopteris type and similar to the English 

 fossils. 



The structure of the spores of Pelletieria is a feature in favour 

 of assigning the genus provisionally to the Schizseacese. The habit 

 of Ceratopteris fronds, the spores of which are of the same ribbed 

 type as, though larger (130 p. in diameter) than, those of Pelletieria, 

 differs much more widely from that of the Wealden species than is 

 the case with Schizaeaceous species. 



The degree of importance to be attached to the size and surface- 

 ornamentation of fern-spores as taxonomic criteria has not been 

 satisfactorily defined ; and, in view of the comparatively large- 

 number of fossil fern - spores now described by palaeobotanical 

 authors, it is proposed to make a critical examination of the spores 

 of recent species. 



1 Fontaine (89) pi. xc, figs. 4 & 4a. 



2 Berry (10) p. 631. 



3 Saporta (94) pi. xvi, fig. 25. 



4 Berry (ll 3 ) pi. xviii. figs. 1 & 1 a. 



5 Stopes & Fujii (10) p. 6. 



6 Eaciborski (94) pi. xii, figs. 8, 11, etc. 



