1883.] Anomalous Oolitic and Palceozoic forms of Vegetation. 225 



bearing ferns of tlie Palaeozoic strata, these spore-bearing fronds are 

 reduced, by the non-development of the cellular parenchyma, to little 

 more than the skeletonised venation ; and it is so in this instance. 

 As Mr. Kidson has shown in his memoir,* the sporangia are oval 

 (Fig. 6a, h), and planted on the rachis (Fig. 6a, a) or midrib of the 

 pinnule in two parallel rows, those of each row alternating with those 

 of the adjoining one. No annulus is present, but there is a single 

 terminal orifice (Fig. 6a, c), through which the imprisoned spores 

 have escaped. This form of sporangium is identical in all essential 

 features with that of the recent Dauasa and the fossil Danseopsis, in 



Fig. 6b. 



Sterile leaflets of 

 the same. 



Portions of two fertile leaflets of 

 Sphenopteris lanceolata. 



which, also, each series consists of two rows of sporangia, arranged 

 in alternating order. Fig. 6b represents a fragment of the sterile 

 frond. This combination of a Sphenopterid frond with the sporangia 

 of a Danaea is wholly unknown at the present day. Many other 

 equally remarkable combinations occui* amongst the Palasozoic ferns. 

 The Carboniferous strata have furnished several very remarkable 

 stems, in which the internal structure is perfectly preserved, but to 

 the systematic relations of which we have failed to obtain any clue. 

 One of the most striking of these is that which I have described under 

 the name of Lyginodendron Oldhamiiim,^ of which we have not only 

 Dbtaincd small twigs, but stems, and such numerous casts of the ex- 

 ceriors of stems as prove it to have been a tree of large dimensions, 

 ind abundantly distributed over wide areas; yet we know nothing 

 3ither of its foliage or of its botanical affinities. Fig. 7 represents an 



* ' On the frurtification of the Eusphenopteris tenella and Sphenopteris micro- 

 -arpa^ Royal Physical Society, Edinburgh, April 19th, 1882. 



t ' Organisation of the Plants of the Coal Measures.' ' Phil. Trans.* 1873 

 |)ls. 22-6. ' 



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