PRIMARY STRUCTURE OF CERTAIN PALAEOZOIC STEMS. 341 



me some sections of C. annularis for comparison with our own, and on visiting 

 Strasburg I was able to examine a number of other sections both of that species and of 

 C. Saturni. Neither of the German fossils is specifically identical with the British 

 form, but I could find no grounds on which to base a generic distinction. A small 

 specimen of C. annularis closely resembled Mr Kidston's specimen of C. fascicularis 

 in the character of its tissues, and might, on superficial examination of the sections, 

 have been taken for a part of the same stem. It differed, however, in the more 

 continuous primary xylem, and the less marked enlargement of the outgoing xylem- 

 strands, as compared with the others. In this specimen the rays were usually two cells 

 thick, but often one cell only in thickness near the pith. There was thus little differ- 

 ence in this respect from the British form. In the large specimens, both of C. 

 annularis and C. Saturni, the rays are wider. The pith appeared to present no 

 marked difference from that of C. fascicularis. Count Solms-Laubach has pointed out 

 that in C. Saturni a xylem-strand is sometimes found embedded in the pith, without 

 direct contact with the secondary wood, though not far removed from it (loc. cit., p. 72). 

 I have observed the same thing in one of his sections of C. annularis, and this, as we 

 have seen, is characteristic of all the smaller xylem-strands in our C. fascicularis. C. 

 Saturni, in the greater separation of the individual circum-medullary strands, 

 approaches nearer to our species than does the form C. annularis. The preservation of 

 the Thuringian specimens is, however, such that the exact limits of the xylem-strands 

 are much more difficult to make out than in the British fossil, especially Mr Kidston's 

 specimen. In the shortness of the internodes C. Saturni also agrees with C. 

 fascicularis, and, as we have seen, the phyllotaxis and general course of the xylem- 

 strands were the same, so far as the evidence available can show. 



On the whole, taking into consideration all the characters available for comparison 

 I feel no doubt that the genus Calamopitys is that in which our fossil may most 

 naturally be placed. The form and relative dimensions of the xylem-strands, and the 

 usually uniseriate rays, serve to characterise C. fascicularis specifically. 



2. Calamopitys beinertiana (Goepp. sp.). 



The investigation of this species is based on a specimen collected by Mr Kidston 

 in September 1900 at Norham Bridge on the Tweed; the horizon (Calciferous Sand- 

 stone Series) is similar to that of the Dumbartonshire specimen of C. fascicularis. Mr 

 Kidston had numerous sections prepared by Mr Lomax from his specimen, and from 

 these he himself determined the main points in its structure, and identified the species 

 with the Araucarites beinertianus of Goeppert.* He then very kindly lent me the 

 sections for further investigation, with a view to the inclusion of the species in the 

 present communication. 



The specimen is a rather large one, about 4 cm. in diameter in its present incomplete 



* This identification has since been confirmed, as will be explained below, by comparison with authentic sections 

 of A. heinertianus, for the loan of which I am indebted to Count Solms-Laubach. 



