PRIMARY STRUCTURE OF CERTAIN PALEOZOIC STEMS. 345 



specimen with the Araucarites beinertianus of Goeppert was established by Count 

 Solms-Laubach in conjunction with Stenzel, whom he consulted. 



The preservation is decidedly better than that of the Tweed specimen. The pith 

 (about 8 mm. in diameter) contains three sclerotic nests,* and agrees in every respect with 

 that of our plant. At three points distinct mesarch strands of primary wood are 

 present ; two of these belong to outgoing leaf-traces, while the third, which is smaller, 

 has not yet begun to pass out. At several other places small strands of tracheides, 

 apparently primary, can be recognised ; most of these were no doubt endarch in their 

 development, and they show no clear cases of mesarch arrangement. The secondary 

 wood, in both transverse and longitudinal section, shows essentially the same structure 

 as in the Tweed specimen, except perhaps that biseriate medullary rays are somewhat 

 more frequent. 



Mr Kidston, who has also examined Count Solms-Laubach's sections, agrees with . 

 me that they remove all doubt as to the specific identity of the British specimen with 

 the Araucarites beinertianus of Goeppert. 



The chief results relating to C. beinertiana are the following : — 



(1) The relatively large pith contains 'sclerotic nests' resembling those in the pith 

 of Lyginodendron. 



(2) Around the pith, and in contact with the secondary wood, numerous primary 

 xylem-strands, sometimes laterally confluent with one another, are disposed. 



(3) The primary strands attain their largest size where they enter the wood ; at this 

 point they resemble the corresponding bundles in C. fascicularis, and are of mesarch 

 structure. 



(4) The small strands are more usually endarch, and sometimes of a horse-shoe form, 

 the opening being turned towards the pith, and the protoxy]em lying in the concavity 

 of the strand. 



(5) A single strand constitutes the leaf-trace, where it enters the secondary wood. 



(6) The secondary wood has a regular Cordaitean structure, with medullary rays 

 seldom more than one cell thick. 



(7) A scale-bark was formed on the older stems. 



The reasons for placing this species in the genus Calamopitys are apparent at once 

 from the foregoing description. The detailed structure of both primary and secondary 

 wood is so closely similar in the two species, that if C. fascicularis is rightly placed in 

 Unger's genus, it is impossible to doubt that the other species must accompany it. 

 Naturally, both determinations, though resting, as it seems to me, on good grounds, 

 must be regarded as provisional until the characters of the cortex and leaf -bases are 

 known. In the meantime, it is interesting to note that in the same beds which yielded 

 the specimen of C. beinertiana, Mr Kidston found a petiole — provisionally named by 

 him Rachiopteris multifascicularis — which presents very much the same structure as 

 the small Kalymma-like leaf-bases borne on the stem of Calamopitys Saturni. 



* Solms-Laubach, loc. cit., p. 208. 



