The Fossil Plants of the Coal Measures. 67 



ZYGOPTERIS GRAYIL* 

 Medulla. 

 Transverse. 



p. — p. 156 Fig. \a, C.N. 1832. The medullary cells have disappeared. 

 See also 264a. Medullary cells preserved in C.N. 1919D. 



Z YGOPTERIS LA CA TTII. Renault. 

 Transverse. 



F.— p. 696, Fig. 45, C.N. 201. p. 296, Fig. 47, C.N. 214. 

 Longitudinal. 



F. — p. 696, Fig. 43, C.N. 212. Tracheids barred. 



For secondary branches passing off from the primary axis consult 

 C.N. 1808 to 1812; for barred and recticulate tracheids in the 

 same bundle see C.N. 181 2. 



ZYGOPTERIS DI-UPSILON. Will. 

 Transverse. 



K.— p. 537, Fig. 90, C.N. 216. 

 Longitudinal. 



K.— p.538, Fig. 91, C.N. 218. 



For longitudinal sections of Fig. 90c see C.N. 220c. 

 Ditto Fig. 9of see C.N. 2i9f. 



Ditto Fig. 9oh see C.N. 218, 220, and 22ih. 



RACHIOPTERIS. Will. 



This group comprehends a number of apparent fern 

 structures, from amongst which no very definite sub- 

 divisions can be established worthy of having assigned to 

 them distinctive names. They will, therefore, retain their 

 present provisional name of Rachiopteris, until more can be 

 ascertained respecting their several mutual relations. 



RACHIOPTERIS INS IGNIS. Will. 

 A rare type, the Tracheids of which are very liable to 

 be filled with Tylosa. 



Transverse. 



K. — p. 506, Fig. 19, C.N. 265. Fig. 20, the central vascular bundle of 

 Fig. 19 further enlarged, 

 p. 506, Fig. 22, Tracheids devoid of Tylose, C.N. 267. 

 Longitudinal. 



K.— p. 506, Fig. 21, C.N. 265. See also C.N. 266B. 



Transverse. 



p. 507, Fig. 23. Section of the bundle of a secondary branch 

 issuing through the Cortex of Fig. 21. 



* In memory of my old and distinguished friend, Asa Gray. 



