88 



E. H, Sellards — Codonotheoa. 



for convenience will be spoken of in this paper as spore-bear- 

 ing segments, or simple segments. The distribution of the 

 bundles to the segments is characteristic. Each individual 

 segment is supplied not by the two bundles resulting from the 

 dichotomy of a single main strand, but receives one bundle 

 from each of two adjacent strands (compare figs. 1, 4, 11, 15, 

 and the plan of structure, fig. 5, PI. YIII). This peculiarity in 

 the arrangement of the bundle system can be verified from 

 numerous specimens, and is one of the prominent structural 

 features of the organ of fructification. The free tips of the seg- 

 ments occasionally stand open, thus retaining in part their 

 original shape, owing probably to their having been quickly 

 buried in sediment. By carefully removing the matrix which 

 fills the cone-shaped cavity enclosed by the segments, it is pos- 

 sible to examine the six parts in place. The two figures, 14 

 and 15, illustrate a specimen worked out in this way, as seen 

 from the two sides. The matrix filling the cavity formed by 

 the expanded segments w^as removed intact and has the shape 

 of a cone flattened laterally, on which is preserved the impres- 

 sions of the six spore-bearing segments. On refitting the two 

 parts of the nodule together, there results an elliptical cavity, 

 large at one end corresponding to the 

 top of the organ, and becoming smaller 

 and disappearing toward the crushed 

 base. The shape of the organ is thus 

 23artly preserved in this nodule, being 

 simpl}^ compressed laterall3\ On looking 

 into the cavity a very satisfactory idea 

 of the shape and arrangement of the 

 parts, and of the whole organ as it 

 appeared in life is obtained. The outline 

 restoration of this fructification given in 

 the accompanying text figure is based on 

 this and similar specimens. The plan 

 of structure of the organ (fig.- 5, PL YIII) 

 represents the hollow top as unrolled and 

 the solid base as cut through the center 

 and laid open. The section is made to 

 pass between segments I and YI, hence 

 directly through strand number I. The 

 letter 'c marks the bottom of the cavity 

 enclosed by the segments. 

 Considerable variation in size is evident in tlie series of 

 specimens. Those of an average size measure 3 to 5"" from 

 the base to the tips. The width at the top is about l-J'"". The 

 segments above the point where they become free are l-J to 2^"' 

 long and 2J to 3""™ wide. The petiole is incomplete, the longest 



Codonotheca ; restoration 

 of the spore - bearing 

 organ. Natural size. 



