LYCOPODIALES— LEPIDODENDEB^— OMPHALOPHLOIOS. 223 



branch, nearly the full width of which is seen in PI. LXVII, Fig-. 2. Here 

 we see again a type of foreshortened, truncated bolster, comparable in form 

 to that of Lepidodendron dypeatum Lx. Within the bolsters we have a very 

 obtuse-angled prominence occxipviug a position at the base of the large 

 boss. This transverse or flatly deltoid scar may be regarded as represent- 

 ing the horizontal side of the oval-triangular central area in the specimens 

 previously noted. Within this angle, the thickened walls of which are 

 suggestive of the leaf scai', we see the horseshoe-shaped loop, including one 

 or two small cicatrices. Indications of the more orbicular or prominent 

 development of the large boss are seen on the cortex on the left or in the 

 partially decorticated area on the lower right. 



A better understanding of this fragment, which has been removed from 

 the left branch of the trunk illustrated in PI. LXVII, Fig. 1, may, however, 

 be reached by an inspection of the opposite side of the same specimen, which 

 is shown enlarged to twice the natural proportions in PI. LXVIII, Fig. 1. The 

 conditions seen on the surface of the cortex of this specimen are as follows: 

 Within a broad, diagonally truncated bolster, suggestive of those of certain 

 Lepidodendra, we have, as before, near the middle, a prominence in the 

 form of a very obtuse angle, opening upward.^ The protruding walls of 

 this angle rise slightly and increase in thickness in approaching the center, 

 where they in some instances form a very low deltoid area. The peripliery 

 of this transverse area exhibits for a distance of from 1.75 to 2.5 mm. 

 on either side of the center a rugose surface of carbonaceous matter, sur- 

 rounded apparently by a line of separation. The area inclosed by this 

 fractured carbonaceous rim can hardly be anything else than the leaf cicatrix. 

 And I may add in this connection that none of the other specimens on 

 which the outer tissue is preserved seem to show any other definite evidence 

 of fracture or separation on the surface of the bolsters. From the lateral 

 angles of these leaf scars, which are often slightly crescentic, pass narrow, 

 vanishing ridges, which may lie in the same direction as the corresponding- 

 side of the cicatrix "angle," or tliey may curve somewhat upward before 

 vanishing in the border of the large boss which they help to define. The 

 vanishing ridges and crescentic prolongations probably play an important 



' The orientation of the figure is based on the place of the fragment in the dichotomous trunk, 

 PI. LXVII, Fig. 1. The interpretation of this prominence as leaf scar, though somewhat tentative, 

 preserves the Lepidodeudroid analogy in the holsters. 



