232 



to figure the more characteristic examples of these curious 

 jointed stems. It is somewhat interesting to observe that all 

 the varieties of stems have branching whorls (generally five) at 

 regular intervals, with an occasional one or two odd " auxi- 

 liary arms" springing irregularly from the axis between the 

 regular whorls. The three variously sculptured varieties 

 may belong to different parts of the column or its auxiliary 

 arms. The calyx of these stems has not yet been observed. 



No. 1 represents a large round stem composed of articu- 

 lated joints of an irregularly moniliform character ; joints 

 from about 12 to 15 millimetres in diameter; articulating 

 surfaces, marked with fine radiating striae near the margin ; 

 surface of stem ornamented with somewhat distant, raised 

 annular ribs or nodes, each about 5 to 6 millimetres apart, 

 the flattened and constricted interspaces with 5 or 6 annular 

 lirae, a large and small one usually alternating. At regular 

 intervals, about every fifth of the larger annular nodes, there 

 is a still larger node, from which five "auxiliary arms" 

 radiate outwards and upwards. The node is somewhat 

 swollen at the junction of each auxiliary. The whole of the 

 surface rings on some of the specimens seem to be crossed 

 by very fine oblique striae, giving them a granular appear- 

 ance. The different parts of the stem, however, show great 

 variation in sculpture, although preserving the general 

 moniliform character. In parts of about 10 millimetres in 

 diameter the nodes are less distant, and the intervening 

 annular lirae are fewer and relatively coarser. The " alimen- 

 tary canal " is central, conspicuous, though ill-defined. There 

 is an appearance of a pentagonal form in some sections of 

 the alimentary canal. 



No. 2 is a stem composed of simple, regular ovate joints, 

 generally more flattened on one side than on the other. 

 Each joint is regularly divided by a well-marked suture 

 about 3 millimetres apart, sometimes showing the crenulated 

 edges of the striae marking the articulating surfaces ; the 

 surface of each ring is simple and flatly rounded. Alimen- 

 tary canal exceedingly fine, sub-central ; articulating surface 

 ornamented with fine striae, longest and most marked on the 

 side most distant from canal. At distant intervals there is. 

 a joint somewhat larger, carrying two auxiliary arms. This 

 joint is divided in the middle by a very fine annular suture, 

 which is well marked in the junction scar of auxiliary branch. 

 Greatest diameter, 12 to 13 millimetres ; smallest diameter, 7 

 millimetres. 



No. 3 is a simple stem like No. 2, but smaller and more 

 rounded. From a polished section, however, it is clear that 

 in the earlier stage of growth it was somewhat oval and more 

 flattened on one side, like No. 2, and that the alimentary 



