Calamite from the Middle Coal-measures. 131 



Division B. — Ribs on the stem not alternating at the 

 joints or nodes. 



Group IV. ASTEROCALA MITES, Schimper. 



Asterocalamites, Schimper, Terrain de Transition des Vosges, p. 321 



(18G2). 

 Arch(eocalamites, Stur, Culm Flora, p. 2 (1875) ; Weiss, I. c. part ii. 



p. 141 (1884). 



Branch-scars irregularly distributed. Joints unequal in 

 length. 



Example : — Calamites scrohiculatus^ Schlotheim, sp. 



Eucalamites {Calamites) bi'itannicus, Weiss, MS. (PI. VII.) 



Description. — Stem : joints as long as broad, outer surface 

 only faintly ribbed, with here and there transverse wrinkles. 

 Nodal lines sharp and distinct, bearing a row of chain-like or 

 in part separated, transversely- oval leaf-scars with a central 

 cicatricule. Branch-scars large, immediately above the nodal 

 line, transversely elliptical, with concentric zones, distant from 

 each other, only a few in a whorl on each joint (on the surface 

 of the specimen figured two branch-scars are seen on one 

 node and one on the other), somewhat irregularly placed, not 

 regularly alternathig. On the upper nodal line between the 

 two large scars occurs a small round scar. 



Remarks. — This Calamite, from having branch-scars deve- 

 loped on each node, belongs to the group of Eucalamites, but 

 shows also affinities with the Galamitina in the form and 

 '* chain-like " arrangement of the leaf-scars on the nodal line ; 

 the transversely elliptical leaf-scars are somewhat similar to 

 those of Calamitina Wedekindi, Weiss *. It also exhibits 

 in the oblique though not exactly alternating position of the 

 branch-scars on the neighbouring nodal lines some similarity 

 to Eucalamites [Calamites] cruciatus. The fossil, which is 

 the impression of the outer surface, shows two joints and a 

 portion of- a third one, and exhibits here and there transverse 

 wrinklings, somewhat like those on the surface of the speci- 

 men given in ' Steinkohlen-Calamarien,' part ii. pi. xvii. 

 figs. 2 and 3, but not so strongly expressed. These probably 

 indicate the drying and contraction of the outer surface of the 

 stem before fossilization. The outer surface further shows 

 peculiar elongated elliptical marks with a central depression, 

 situated below the nodal lines and similar to those of pi. i. 



* ' Steinkolileu-Calamarien,' ii. p. 88, pi. xvii. tig. 1. 



9* 



