E. M, Sellarcls — CodonotKeca. 91 



strands running throngli them. On the contrary, the organ 

 appears to be made up of six lamina-like fertile divisions, united 

 in a circle at the base so as to enclose a central cavity, the 

 sporangia being borne on the inner side and probably partly or 

 entirely immersed in the fleshy tissue. 



It seems wholly improbable that Codonotheca can have any 

 direct or close connection with the mosses or other plants lower 

 in the scale of development than the vascular cryptogams. It 

 is true that a water-conducting tissue is rather well developed 

 in the stem of some mosses, and to some extent in the sporo- 

 gonia of a few genera, but a well-developed vascular system, 

 such as this organ possesses, is at present entirely unknown in 

 any plant below the Pteridophytes. On the other hand, the 

 unusual structure of the reproductive organ makes it difflcult 

 to determine the systematic position of the genus among the 

 vascular plants. The spore-bearing region of the known Paleo- 

 zoic and recent Equisetales is typically a cone formed by the 

 shortening of the internodes of the main axis, or of the axis of 

 a branch. The cone is made up of several to many nodes and 

 internodes. Each node may bear a whorl of fertile sporophylls, 

 or fertile and sterile whorls may alternate or bcA^ariously modi- 

 iied according to the genus. In the extinct Splienophyllales, 

 the cone is also formed by a shortening of the internodes of the 

 axis, and the fertile sporophylls are borne in whorls at the 

 nodes. The sporangia of the Lycopodiales are borne. at the 

 base of the sporophylls, which usually^ form a cone. The ferns, 

 although a more varied class, seem to include no type whose 

 fundamental structure is comparable to that of Codonotheca. 

 Some species of Schizcea, as S. joennida^ have a cluster of simi- 

 larly shaped sporangia-bearing divisions, but these have exter- 

 nal dorsal sporangia with a ring of thick-walled cells at the top, 

 and lack entirely the unusual cyclic arrangement and the 

 fleshy petiolate base characteristic of Codonotheca. It is also 

 evident that this new type can have no connection with such 

 ferns as the Hymenophyllaceas, in which the elongated recep- 

 tacle, bearing the sporangia, is surrounded by an indusium-like 

 outgrowth of the lamina. The extinct fernlike genera Botry- 

 ojyteris and Zygojpteris^ which have sporangia clustered at the 

 ends of slender peduncles, do not seem to admit of comparison 

 with Codonotheca except on the hypothesis, which appears to 

 me untenable, that the six divisions of the organ are so many 

 large sporangia. 



For many years numerous plants have been known from the 

 Paleozoic, having a stem structure resembling that of the ferns 

 on the one hand, and the cycads on the other, but so different 

 in many ways from both as to be with difiiculty included in 

 either. Since 1899'^ these plants have been united to form an 



* Potonie, Lehrbuch der Pflanzenpalaeontologie, p. 160. 



