BRITISH CARBONIFEROUS PLANTS 139 



to the Lepidostroboid type. This cone which belongs to 

 B. mundum, has a large ligule and the sporangia have only a 

 very narrow attachment to the sporophylls. 



Miss Berridge (16) has described two new specimens of 

 Spencerites insigm's, which, " particularly in the absence of 

 Dictyoxylon structure in the cortex, the more ovoid form of the 

 sporangia " . . . " and the greater tangential width of the sporo- 

 phyll-head," differ from those previously described. Mrs. D. H. 

 Scott (54) has also figured and discussed the megaspore of 

 Lcpidostrobus foliaccus. 



The structure of Stigmaria has received further attention 

 at the hands of Weiss (71), who has described an interesting 

 case of a Stigmarian axis in which centripetal primary wood 

 occurs. 



The stem of the genus Sigillaria, the structure of which 

 was very imperfectly known until quite recently, at any rate 

 so far as British examples were concerned, has now been 

 worked out in the case of no less than three species, in all 

 of which it has been possible fortunately to correlate the 

 external features with the internal structure. These three 

 species all belong to the " ribbed section " of the genus or 

 Eusigillariae. The Favularian type, Sigillaria elegans, was 

 described by Kidston (32) in 1905, the structure of the cone- 

 scars being illustrated and the general evolution of the genus 

 discussed. 



More recently the writer, in conjunction with Hugh 

 Thomas (11) has illustrated the structure of S. scutellata, a 

 Rhytidolepis type, on which species, with the addition of 

 S. mammillaris, Kidston (35) has also issued a short note. In 

 S. scutellata it was found that the leaf-trace, when traversing 

 the leaf-base, possessed a double xylem strand ; consequently 

 the leaves, previously described by Scott (45) in 1904 as Sigilla- 

 riopsis sulcata, are the leaves of a ribbed Sigillaria. Kidston also 

 arrived at the same conclusion independently. 



Miss Coward (18) has described the structure of a decorticated 

 (Syringodendron) specimen of Sigillaria. 



Thus we see that the study of Palaeozoic Lycopods has 

 recently yielded many interesting results. Yet much still 

 remains to be accomplished, especially along the lines adopted 

 in the above-mentioned memoirs. The correlation of the 

 external features with the internal structure, a path of investi- 



