232 CORDAITEAE [CH. 



separated from one another by 2 — 3 or it may be as many as 5 

 finer ribs or interstitial 'veins.' A statement by Weiss that in 

 Germar's type-specimen the longitudinal ribbing of the lamina 

 is very imperfectly preserved confirms the scepticism that is justly 

 felt as to the validity of this character as a satisfactory specific 

 criterion. 



The incomplete example shown in fig. 466, A, is 19-5 cm. 

 long and has a maximum breadth of 3-5 cm., but the complete 

 leaf was much larger and tapered gradually to the comparatively 

 broad and sHghtly concave or amplexicaul base. The narrow 

 eUiptical proximal end of a specimen figured by Kidston^ from 

 the Middle Coal Measures of Yorkshire is 2-8 cm. broad indicating 

 that the tangentially expanded leaf-scars on a branch recently 

 deprived of its foHage must have been a conspicuous feature. In 

 his synonymy of this species Kidston^ includes Knorria taxina, 

 a species founded by Lindley and Hutton^ on a piece of stem from 

 the Coal Measures of Newcastle. The type-specimen, as Mr 

 Howse* states, is much larger than the published drawing and 

 closely resembles in the decurrent leaf-bases with broad apices 

 the piece of stem represented in fig. 466, C, which Kidston identifies 

 as C. frincifolis. Geinitz^ refers to this species the seeds named 

 Cordaicar-pus Cordai (Gein.), but there is no evidence of connexion. 

 Kadston^ points out that this seed is rare in Britain : he believes 

 that Cordaianthus Pitcainute (Lind. and Hutt.) is probably the 

 inflorescence of C. 'princi'palis . 



Cordaites -princi'palis occurs in both Carboniferous and Permian 

 strata. The leaves described by Lesquereux^ from Pennsylvania 

 as G. Mansfieldi agree closely with C. principalis. Another 

 similar or possibly identical form is represented hj C. Ottonis 

 Gein. 8 



1 Kidston (93) A. PI. Vf. fig. 16 ; (02) B. PI. LXiv. fig. 3. 



" Kidston (93) A. p. 352. ^ Lindley and Hutton (33) A. PI. 95. 



* Howse (88) p. 112, fig. 7. 



» Geinitz (55) A. p. 40, PI. xxi. figs. 7—16. 



« Kidston (93) A. p. 355. 



' Lesquereux (80) A. p. 537, Pi. Lxxvni. 



8 Geinitz (62) p. 148, PI. xxxv. 



