IX] CALAMOCLADUS. 289 



Prof. Zeiller informs me that in the type-specimen on which 

 Brongniart founded the species, P. australis, the sheath appears 

 to be closely applied to the stem with a verticil of narrow 

 spreading segments radiating from its margin. It may be, 

 therefore, that in the Australian form there was not such an 

 open and cup-like sheath as in P. indica: but it would be 

 difficult, without better material before us, to feel confidence in 

 any well marked specific distinctions between the Indian and 

 Australian Phyllothecas. 



On the broader stems, such as that of fig. 67, we have 

 clearly marked narrow grooves and broader and slightly convex 

 ridges, which present an appearance identical with that of some 

 Calamitean stems. In the specimen figured by Bunbury^ in his 

 PI. X, fig. 6, there is a circular depression on the line of the 

 node which represents the impression of the basal end of a 

 branch ; on the edges of the node there are indications of two 

 other lateral branches. The nature of this stem-cast points 

 unmistakeably to a woody stem like that of Calamites. The 

 precise meaning of the ridges and grooves on the cast is 

 described in the Chapter dealing with Calamitean plants. 



Grand'Eury'^ in his monograph on the coal -basin of Gard, 

 has recently described under the name of Calamocladus fron- 

 dosus what he believes to be the leaf-bearing axes of a 

 Calamitean plant. The thicker branches are almost exactly 

 identical in appearance with the broader specimens of Phyllo- 

 theca. The finer branches of Calamocladus bear cup-like leaf- 

 sheaths which are divided into long and narrow recurved 

 segments (fig. 67, B), precisely as in Phyllotheca. These com- 

 parisons lead one to the opinion that the Phyllotheca of 

 Australia and India may be a close ally of the Penno- 

 Carboniferous Calamitean plants. The form of the leaf-whorls 

 of Annularia (Calamarian leaf-bearing branches) and of 

 Calamocladus is of the same type as in Phyllotheca ; the 

 character of the medullary casts is also the same. The nature 

 of the fertile shoot of Phyllotheca described by Schmalhausen 

 from Siberia, with its alternating whorls of sterile and fertile 

 leaves, is another point of agreement between this genus and 

 1 Bunbury (61). " Orand'Kury (90) p. 231. 



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