LEPIDODENDREAE. 205 



In the Knorriae, in which this lateral branching is particularly common, the 

 thinner lateral Branch will often impede the further growth in thickness of 

 the main stem, and then the base of the side-branch is seen to be imbedded 

 in a lateral groove which forms on the stem. The branch is then usually 

 found to be broken short off, and the appearance is sometimes as though 

 this fracture took place before the specimen was imbedded in the stone ; 

 this is .the case when the lateral furrow terminates suddenly with a curved 

 outline just above the place of fracture, and the stem at once recovers the 

 original form of the transverse section. 



Though such large portions of the head of Lepidodendrae have come 

 under observation, yet, as might be expected, it is only in a few cases that 

 the main ramifications have been seen attached to the stem which bore 

 them. From these few discoveries it cannot be distinctly gathered, whether 

 the considerable differences have specific or only individual significance ; 

 still they are so strong that we necessarily incline towards the former view. 

 Among the first stems which have a claim to precedence of notice is the 

 one described by Lindley and Hutton 1 as Lepidodendron Sternbergii. 

 It was discovered in the roof of a seam in Jarrow mine in England, and 

 was laid bare from the base to the branches of the crown, a length of 

 thirty-nine feet. The stem, which is three feet thick in its lower portion, is 

 flattened, and, if I understand the accounts properly, shows the Bergeria- 

 character on the surface. It branches dichotomously in the most regular 

 manner, and its crown is preserved through three generations of bifurcating 

 shoots, but is then broken off by a small fault. In Sternberg's 2 famous stem, 

 on the other hand, which was discovered in the roof of the lower Radnitz 

 seam at Svinna in Bohemia and with its branches is four metres in length, 

 the crown begins with two branches placed exactly laterally right and left 

 and at a distance of forty-six centimetres from one another; we know 

 nothing of their subsequent ramifications, as they are broken off near the 

 base. The first regular bifurcation is forty-six centimetres further down 

 the stem, and this is repeated twice in the branches and then passes into 

 lateral branching. We are indebted to Stur 3 for the description of a third 

 case. The colossal stem, five hundred and twenty-two centimetres in 

 length and sixty-three centimetres in diameter at the bottom, had had its 

 head broken off down to the lowest and exactly lateral branch ; it was 

 found in the Alberti mine at Hruschau in Bohemia, and was carefully 

 drawn as it lay. The one branch, which is thirty-one centimetres in 

 diameter at the point of attachment and narrows rapidly, forms a right 

 angle with the stem and shows sympodial branching. 



Certain forms of Lepidodendron have been collected into a group and 



1 Lindley and Hutton (1), vol. Hi, t. 203. 2 Sternberg, Graf von (1), Heft 1-4, t. I. 3 Stur 

 (5), p. 224. 



