338 



PALAEOZOIC TIME — CARBONIFEROUS AGE. 



kernel; c, the complete nut; d, the husk or rind enclosing the nut. Fig. 572 is 

 Cardiocarpum samarse/orme (the name of the genus, from xapbiov, heart, alludes to 



Figs. 571-574. 



Fig. 571 a, b, c, d, Trigonocarpum tricuspidatum ; a, the nut ; b, the kernel ; c, the complete 

 nut; d, the husk or rind; 572, Cardiocarpum samaraeforme ; 573, C. elongatum; 57^, C. 

 bicuspidatum. 



the common cordate form of the seed) ; fig. 573, C. elongatum ; fig. 574, C. bicus- 

 pidatum. The Cardiocarpa are supposed to be the fruit of Lepidodendra. 



6. Ferns. — The ferns are mostly of the low herbaceous kinds, al- 

 though a few tree-ferns occur. Some of the fronds were six to eight 

 feet in length. 



In one group of Ferns, the Neuropteridse, the leaves or leaflets have no mid- 

 rib, as in Cyclopteris, Noeggerathia, Odontopteris, and Neuropteris. In another 

 group, the Sphenoptcridse, the leaflets or lobes have a mid-rib slightly distinct, 

 but it fails before reaching the apex, and the veins do not emerge from it, 

 as in Sphenoptcris and Hymenophyllites. In a third, the Pecopteridse, the mid- 

 rib is very distinct, and the veins emerge from it more or less obliquely, as in 

 Alethopteris, Pecopteris, Callipteris, Asplenites. 



Fig. 566 represents the scar on the surface of an American species of fossil 

 tree-fern, Caulopteris jmnctata Lsqx., from the Gate vein, 

 Pennsylvania. For comparison, the scar of a modern tree- 

 fern, fig. 575, is here given, from the species Cyatkea compta, 

 occurring in the islands of the Pacific. With the growth of 

 the tree (see sketch near middle of frontispiece), as new 

 fronds are unfolded, the old ones drop off, each of which 

 leaves its sear analogous to the above. The manner in which 

 the fronds of ferns unroll as they expand is shown in the 

 figure here referred to. 



Fig. 576, Neuropteris Losehii Brngt., and fig. 577, Neu- 

 ropteris hirsuta Lsqx., from figures by Lesquereux, both very 

 common in the Upper Coal measures in Ohio and Kentucky, 

 and the former particularly abundant in the Pomeroy bed. 

 Fig. 579, Pecopteris arborescens Brngt., common in Penn- 

 sylvania and Ohio. P. Cyathea Brngt., and P. unita Brngt., 



Fiff. 575 



Scar of a recent tree- 

 fern (xy 2 )- 



