30 Mr E. Kidston on the 



fruit consists of eight segments. The segments are formed 

 by a constriction which corresponds in position to the nodes 

 of the axis. On the circumference of each internodal por- 

 tion of the fruit there have been from ten to fourteen 

 longitudinal elevations which bore sporangia ; these in the 

 young state appear externally as quadrate bodies, having 

 their angles rounded and a shallow notch on each side. 

 The sporangia open in a definite manner, by a cleft passing 

 from the apices of the angled corners towards their centre ; 

 and by the margins of the split sporangia becoming deflexed 

 the so-called calyx-segments are formed. 



The spike is also attached to a stem composed of nodes 

 and internodes, which branched in a more or less equal 

 dichotomous manner, and bore, at the extremities of the 

 dichotomous branches, cones or spikes. 



The stem also shows traces of longitudinal furrows. 



Verticillate dichotomously formed leaves are given off 

 from the nodes of both spike and stem. 



From such important structural evidence it appears no 

 longer possible to regard Pothocites as a Monocotyledon, 

 and I am inevitably led to the conclusion that Pothocites is 

 not the inflorescence of an Aroid, but the fructification of 

 a Calamitaceous plant. 



But from the material before us we can, I think, place 

 the genus Pothocites in a much more defined systematic 

 position than merely indicate its nature to have been that 

 of a Calamitaceous plant. 



The characters by whicli we are enabled to show its more 

 particular afiinity are the leaves, fruit, and stem. 



The foliage is distinctly dichotomous in its structure, as 

 seen in the example from Eskdale. 



The furrows on the stem are too indistinct to show 

 whether or not they alternate at the nodes.* 



* It is an unsettled point amongst vegetable palseontologists whether the 

 stems of Calamitcs, in their natural condition, possessed a smooth or a furrowed 

 bark. Some contend that the outer surface of the stem was longitudinally 

 furrowed, others that it was quite smooth, and that the furrows have been 

 imparted by external pressure, or even that the fluted casts, which are of so 

 common occurrence, are merely the interuiJ casts of the hollow stems. But it 

 is generally admitted that when Calamitcs occur as mere casts or impressions 

 they almost invariably show a fluted exterior. Hence, in dealing with fossils 

 in this condition (a condition in which all the specimens mentioned in these 

 notes occur), tlie furrowing of the stem becomes of generic value, whatever 

 structure the outer surface of the stems may have had when growing. 



