CARBONIFEROUS LYCOPODS AND SPHENOPHYLLS. 95 



Staffordshire, showing an approximation of the leaf-scars on the 

 lower half of the fossil. Similar conditions are shown on a 

 specimen of Sigillaria mamillaris, Brongt., given by Lesquereux, 1 

 and on Sigillaria Sauveuri, figured by Zeiller, 2 and many other 

 cases can be cited. 3 



I possess a specimen of Sigillaria Sauveuri, Zeiller, from 

 Longton Hall Colliery, Longton, Staffordshire (No. 2199), for 

 which I am indebted to Mr. John Ward, F.G.S., which shows a 

 similar approximation of the leaf-scars to that shown on the 

 specimen figured by Zeiller. Another specimen in my collec- 

 tion which I have provisionally referred to, Sigillaria Boblayi, 

 Brongt. (No. 1879), not only shows an approximation and lessen- 

 ing of the leaf scars, but a sudden narrowing of the ribs, which 

 must have caused a great reduction in the diameter of the stem. 

 All these specimens probably represent an enfeebled state of 

 growth; in some cases the enfeebled portion is succeeded by the 

 normal condition of the species as to the size of the leaves and 

 their distance apart. It is difficult to suggest a cause for these 

 apparently enfeebled states of growth; probably they may have 

 resulted from unfavourable climatic conditions. 



In the Clathraria Section of Sigillaria the cone-scars are dis- 

 tributed on the stem in two distinct modes of arrangement. 



On the typical form of Sigillaria Brardii the cone-scars form 

 an irregular girdle round the trunk, and are placed in the furrows 

 which divide the leaf-cushions. Normally they are circular with 

 a raised border, and in the centre show the cicatrice of the 

 vascular bundle which passed into the cone pedicil. The cone- 

 scars are, however, usually deformed from the pressure of the 

 surrounding leaf-cushions, and in turn they produce in most 

 cases a great deformation of the leaf-cushions and leaf-scars. 

 The cone-scars measure about |^ inch in diameter, but their size 



1 Coal Flora, Vol. III., PI. CVIIL, fig. 6. 1884. 



2 Flore joss. Bassin houil. d. Valenciennes, PI. LXXXIV., fig. 1. 1886. 



3 Potonie, "Die Wechsel-Zonen-Bildung der Sigillariaceen." — Jahrbuch 

 dtr Kbnig Preuss. Geol. Landesavstalt fur 1893 (1894), p. 24, Pis. III.-V. 

 Freeh., Lethcea geognostica, 1 Theil. Lethcea palceozoica, 2 Band, 2 

 Lief., PI. L6, fig. 12 (Sigillaria Brardii). Stuttgart, 1899. Sigillaria 

 Brardii and Sigillaria dimorpha { — Sigillaria camplotcenia, Wood sp.). 

 G6ol. et Paleont. du Bassin Gard., PI. XI., fig. 1, and PI. IX., fig. 7. 



