8 Watson, Oh the Ulodouli-oid Scai . 



opposite rows, for example, Lcpidodciidron sclaginoidcs Car., 

 or vascnlai-c Binney (see Weiss and Lomax, :05), and 

 Lcpidodciidron Hickii Watson (see Watson, :07). 



Against the branch theory, the evidence of three 

 specimens will be used, they are — 



1. The specimen described and figured by Professor 

 D'Arcy Thompson ('8o) as shewing a cone in connection 

 with a Ulodendroid scar. 



2. The specimen referred to by Professor D'Arcy 

 Thompson and figured by Mr. Kidston in '85. 



3. The specimen figured by Mr. Kidston ('85) which 

 shews a Ulodendroid scar apparently covered by fairly 

 well preserved leaf bases. 



I shall endeavour to shew that these specimens can 

 be explained on the branch theor}-. 



I. The specimen figured natural size by Thompson 

 shews an organ apparently attached to the centre of an 

 ill-defined Ulodendroid scar. A series of Ulodendroid 

 scars is continued below the organ. 



Judging from the figure, the surface of the important 

 Ulodendroid scar is nearly flat, and the organ lying in the 

 same plane is apparently attached only to the umbilicus. 

 The basal end of the organ increases rapidly in diameter, 

 so that at a distance of about 5 cm. from the attachment, 

 the organ is nearly 5 cm. in diameter. 



If the Ulodendroid scars are produced by the 

 pressure of the bases of such cones, they must be very 

 deep, in fact, at least 5 cm. deep, as they are about the 

 same thickness as the diameter of organ at that point. 



From our knowledge of the characters of the cortices 

 of old Lepidodendroid stems, we know that this deep 

 Ulodendroid scar would have to be excavated in a tough 

 and decay-resisting mass of tissue ; how such a mass of 

 tissue could be crushed flat, and the organ, tightly fitting 



