62 NEW YORK STATE MUSEUM 



Halfway up the trunk the leaf cushions are longitudinally more 

 distant, while those near the borders of the specimen exhibit a 

 rhomboidal form, which is clearly in a spiral arrangement, similar 

 to that familiar in the Lepidodendra. Still higher they are nar- 

 rowly rhomboidal, or obscurely fusiform, closely placed, slightly 

 asymmetrical, and partially overlapped obliquely in the same vertical 

 row. In this portion of the trunk the spiral arrangement is very 

 sharp and the vertical costation is obscure except where exagger- 

 ated by lateral pressure along the median zone. In fact the form 

 and arrangement of the cushions are essentially characteristic of 

 the Carbonic Lepidodendrons. They are typical of the Devonic 

 lepidophytic material described by authors as Lepidodendron, 

 though really differing from this genus by the characters of the 

 leaf scar. 



An interesting phase in the preservation of the trunk (seen at 

 two thirds of its length) consists of the aspect of imbricated bracts 

 or slivers. The latter correspond to the casts of the nerve sheaths- 

 passing outward and upward through the cortical tissues which in 

 this region are partially macerated. The structure observed in this 

 portion of the trunk is that sometimes seen also in partly decayed 

 trunks of Lepidodendron, Bothrodendron and Asolanus, and repre- 

 sents the false genus, or condition of preservation, described as 

 Knorria. 



The leaf scars are well shown in the second and third quarters 

 of the specimen. The scar, placed on the upper part of the cushion, 

 is longitudinally oval and is provided with relatively long crescentic 

 lateral cicatricules (parichnoi) that form a horseshoe beneath the 

 nerve trace in the subepidermal impressions. 



• As in most of the other Devonic representatives of this group the 

 leaves seem to have adhered to the bark, even after the branches and 

 trunk had attained considerable size. Short, rather lax, slender, 

 and inconspicuous examples, standing nearly at a right angle to the 

 trunk, may be observed at various points along the periphery of the 

 stem, especially on the left near the top. In form and habit they 

 agree with the leaves of Lepidodendron and Bothrodendron. 



As a whole, the trunk is seen to combine rootlet characters of 

 Stigmaria ; dilation and leaf cushion form and arrangement char- 

 acteristic of Sigillaria in the lower part and of Lepidodendron in the 

 upper portion ; and a Knorria structure similar tO' that found in 

 Lepidodendron, Bothrodendron, and the sigillarian Asolanus while 

 the leaf scars are in character nearest to those of Cyclostigma 

 (Bothrodendron), with which, as well as Lepidodendron, the leaves 



