144 FLORA OF LOWER COAL MEASURES OF MISSOURL 



The relationship of Tceniopteris missowiensis and of other supposed 

 Paleozoic representatives of the Marattiaceje was considered somewhat in 

 full by me- in a special publication on the subject/ 



Localities. — Hobbs's bank, U. S. Nat. Mus., 5556-5560, 5568. Also one 

 specimen from Deep water, U. S. Nat. Mus., 5591. 



EQUISETALES. 



CALAMLTBS Suckow, 1784. 

 Acta Acad. Theod. Palat., voL v, p. 357. Scblotheim, Petrefacteokuude, 1820, p. 398, 



The brilliant results obtained in late years by the English, French, and 

 German investigators of the internal structure of the Calamarian types have 

 thrown great light on the relations of this class of vegetable remains. 



While at first it seemed that the study of the anatomical features of this 

 group would lead to its division into several sections of generic, or at least 

 subgeneric rank, some of these sections being referred to orders far apart in 

 the vegetable world, the widespread interest and increased attention to the 

 subject consequent upon the earlier developments tend lattei-ly to show the 

 relative unity of the Calamarian group, though it is characterized within 

 itself by remarkable diversity and complexity, such as have rendered 

 enigmatic so many of the Paleozoic types. 



From large stems with thin walls like Calamites Suckoivii or C. ramosus, 

 whose superficial structure is interpreted ' as indicating a close relation to 

 the receut JEqimeta, there seems to be a progression to the thick, complex 

 walled species with well-developed secondary woody growth of the Calamo- 

 dendron or Arthro'pikis types. 



Of great interest in this connection are the observations and conclu- 

 sions of Mr. Cormack ^ who has found in Equisekmi maximum that the older 

 nodes possess much more highly developed woody structure than the yomig 

 nodes, with new radially disposed elements and what seem to be cambial 

 cells between the bark and the wood. From a comparison of the structure 

 of the recent plant with that of Calamodendron it would appear that the 



I Bull. Geol. Soo. Am., vol. iv, 1893, p. 119 et seq. 



^Saporta, E6vue g^n. bot., vol. i, p. 584. 



■'Anuals of Botauy, vol. vii, 1893, pp. 63-82, pi. vi. 



