112 Dr. W. C. Williamson on 



Leak-Traces. 

 Transverse, 



BB.— p. II, Fig. 3c", C.N. 380. 

 p. 9, Fig. 7f, C.N. 380*. 

 p. 10, Fig. 8, C.N. 1596. 

 p. 10, Fig. IOC, C.N. 3806. 

 p. 10, Fig. 12, C.N. 1596A. 

 p. II, Fig. 13c', C.N. 380k. 



Longitudinal. 



BB.— p. 10, Fig. 9c, C.N. 38of. 



p. 10, Fig. I lab, C.N. 3806. 

 p. 12, Fig. 19c, C.N. 380m. 



Leaves. — Parichnos and Adenoids. 

 Transverse. 



BB.— p. II, Fig. 14, C.N. 380k. 

 p. 12, Fig. 15, C.N. 380.* 

 p. 12, Fig. i6c,c", C.N. 380b. 

 p. 12, Fig. 17c', C.N. 1596B. 

 p. 12, Fig. 18, C.N., 1596A. 



Halonial Arrested Fructigerous Twigs. 

 Primary Cylindrical Strand. 

 Transverse. 



BB.— p.p. 19, Fig. 26B, 1.', C.I., C.N. 380b. 

 p. 17, Fig. 27I', C.N. 380a. 

 p. 19, Fig. 28a, C.N. 380a. 



Longtititdinal. 



BB.— p. 19, Fig. 29c, b., C.N. IS96D. 

 p. 19, Fig. 29B,« C.N. 1596D 



Type of Lepidodendron mundum. Will. 



A new and very small form. My largest specimen, in- 

 cluding its secondary exogenous xylem, but decorticated, is 

 only "2 in diameter, and my largest corticated, one without 

 any secondary xylem strand, only "3 of an inch, whilst my 

 youngest one (C.N. 405A), including the cortex, is but •033. 

 The primary xylem strand commences as a solid vascular 

 bundle of conspicuous tracheids, devoid of medulla ; but 

 this organ soon makes its appearance in a very minute 

 form, and composed of extremely small cells ; but both 

 individual cells and medulla enlarge as the diameter of the 



