[matthewJ a review OF THE LITTLE RIVER GROUP 107 



show the scars of the branches [leaves?] at the top of the ribs. I 

 have also specimens showing the base of the stem, terminating in an 

 oblique point exactly as in the Carboniferous species and showing that 

 these plants grew in groups or stools in the manner of ordinar}- Cala- 

 mités of the Coal Measures/' 



The following is the diagnosis of this species: — Stems generally 

 broader than the space between the articulations (internodes) ; ribs 

 half-round or plano-convex, obtuse at the articulations, furroivs narrow, 

 obtusely carinate; tubercles or impressions of the bases of the leaves 

 more or less distinctly oval. 



Of this species Lesquereux says, " The stems average seven to 

 twelve centimetres in thickness, when not flattened. The epidermis 

 is very thin, smooth, and the bark also thin, the ribs distinct, the arti- 

 culations somewhat variable, close toward the base. When decorticated, 

 the under surface, distinctly ribbed, is narrowly striate lengthwise, more 

 obscurely so on the outside surface. 



" This most common species of our coal is generally represented 

 in flattened fragments in the shale overlaying the coal, but alwa3is in 

 cylindrical sections of stems in the sandstones. 



" The tubercles are mostly oval, but also sometimes round, half- 

 globular, smooth, placed at the top of the ribs, rarely at their base." 



Having found numerous examples of this species among the 

 material from the strata of the Little Kiver group, and knowing its 

 ver}»- wide range, geologically, extending as it does to the summit of 

 the Palaeozoic formations, it appeared desirable to give the species a 

 closer study than that given to other species of the genus found in the 

 Devonian rocks, especially in comparing it with Coal Measure types, 

 more especially to see how far the length of the joints and the width 

 of the ribs could be depended on for diagnosis. 



Five examples from the Joggin's Mine in Nova Scotia, one upright 

 and round, from the sandstones, and one flattened, from the shales 

 presented the following characters: In the one from the sandstone 

 the base is unusually obtuse and the top is absent, having decayed away, 

 or been broken off at a height of fourteen inches from the base. In 

 this height there are thirteen joints, all with well defined cicatrices of 

 leaf bases, (or roots) showing there was a whorl of such appendages at 

 each node. For one-quarter of the length from the base the joints 

 increase rapidly in length, but for the remainder of the stem do not 

 change more than a few millimetres in length from joint to joint. The 

 section of the stem is oval owing to lateral compression, and the width 

 of the ribs corresponds to this being a fifth narrower on the more con- 

 vex quarter. The width of the ribs is that which we find in many 



