8Pi<:(;;]^[KNs of I'ossrr, woods ix xatal muskum. 351 



same sample: An average length is difficult to determine, 

 and it is safest to state that many of the tracheides appear to 

 have a length of about ()'8 mm. [bordered pits are confined 

 to the radial walls; they are usually in three rows, and 

 exceptionally in four, in the thin-walled spring tracheides, 

 and biseriate or uniseriate in the autumn tracheides. In 

 the spring tracheides the pits are closely contiguous and 

 generally somewhat hexagonal in outline, in the autumn 

 tracheides with one or two rows they may be closely con- 

 tiguous and slightly hexagonal, or more or less separate and 

 scattered when they are rounded in outline. There is also 

 variation in their arrangement ; when in double series the 

 pits of each row may alternate, or they may be in pairs 

 opposite to one another. Diameter of bordered pit 00081 

 mm., central opening generally circular (text-fig. 1, A). 



Medullary rays are numerous, there being an average of 

 about 6 to every millimetre of tangential length : usually one 

 cell thick, varying in height from 3-14 cells, the average 

 number being about 7. Radial length of medullary cells 

 variable; the average is O'lo9 mm., or about four times the 

 average radial width of a tracheide. Average tangential 

 width of medullary ray cells 0"02] mm., and vertical height 

 about 0'027 mm. 



The medullary ray cells communicate with the tracheides 

 by simple oval pits, there being 2-8, more usually 4, of such 

 on the surface of contact between the medullary cell and 

 tracheide. The long axis of the pits may be oblique or hori- 

 zontal. The pits are sometimes narrow and slit-like. 



In some of the specimens the medullary cells contained a 

 homogeneous yellow substance which perhaps represents 

 resin. 



One sample (Mus. No. 11) calls for special remark. The 

 exact locality is unknown. The label attached to the specimen 

 is: "Natal. I'resented by A. J. Maritz, 1888." I have been 

 unable to obtain further information with regard to it, and 

 consequently the geological horizon is unknown, but it is 

 prol)ably Xatal Coal Measures. The fossil is pale bi'own, 



