[MATTHEW] A REVIEW OF THE LTTTLERIVER GROUP 109 



The length of the nodes in these specimens indicate that they came 

 from the main part of the stem, but it will be seen that Coal Measure 

 examples with a similar length of node had ribs considerably narrower. 

 Whether this was accompanied by other diiïerences of foliage, etc., we 

 do not know, but so far as the relief of the ribs is concerned, and the 

 arrangement of the ribs and furrows, the plan of structure of these 

 stems, so widely different in 'age, is similar. 



Calamités geniculosus, n sp. Plate II, Fig 5, and Plate VIII, Fig. 1. 



A species with short internodes and thin epidermis, and showing 

 but weak vascular support. A stem 52 mm. wide has internodes 33 

 mm. apart; the decorticated stem shows six or seven ribs in the space 

 of a centimetre; these ribs apparently are alternate; the diaphragms 

 are weak, and the scars of the leaf bases inconspicuous. 



Leaves long, narrow, rigid, erect, dichotomous at intervals; they 

 are from one to one and a half mm. wide and 70 mm, or more in length, 

 branching at an acute angle; the outer leafing branches are more divided 

 than those next the main stem. 



A portion of a young stem shows more frequent nodes than that 

 above described, and is probably from near the root. The nodes are 

 8 to 12 mra. apart, and have alternate ribs of which about seven fall in 

 the space of a centimetre. A dichotomizing branch from this young 

 stem is 70 mm. long and has five nodes in that distance. The branch 

 is erect and grew at an acute angle from the stem, the leaves extend- 

 ing mostiv on the side away from the main stem; they are erect, are 

 about 1 mm. wide and 30 mm. long; the nodes whence they spring or 

 bifurcate are 2 mm. wide; the dichotomy is sub-regular, several leaves 

 forking at an equal distance from the branch. 



Sculpture. — The stem is smooth when not decorticated, but when 

 deprived of the bark is seen to be minutely striated lengthwise on the 

 ribs. 



In a comparison of this species with Calamités approximatus impor- 

 tant differences appear; the nodes are closer and the vascular bundles 

 weaker; also the bark is quite thin, and the ribs are much narrower. 

 The dichotomous leaves recall those of AsterocaJamites scorhiciiJatus, 

 but the leaves of that species as sho^m by Stur's figure ^ are flexuous, 

 whereas these are stiff and erect. 



Horizon and Locality, Lower Cordaite shale, Fern Ledges, Lancaster. 

 Special bed not noted. 



^Zittel's Palaeontology, Vol. Ill (Plants) p. 171, fig. 133. 



luJ i L I B R A R Y 



