68 



J. WATSON, S.J. LYDON & N.A. HARRISON 



Fig. 30 A, B Sciadopityoides greehoana sp. nov. A, stoma viewed from the inside of the cuticle, V.64587, x 750. B, upper cuticle showing rectangular 

 epidermal cells with median patches of thickening elongated longitudinally over one or more cells: thin sinuous outlines of hypodermal cells also shown, 

 V.64587. X 400. 



their inner and outer edges the guard cell anticlinal walls are shallowly 

 cutinized (Figs 28A; 29F). Polar appendages are also a characteristic 

 feature of this species but the extent to which they are developed is 

 variable (Figs 28 A; 29F). The ventral guard cell wall may also be 

 partially cutinized in some stomata (Fig. 29D, H). 



Discussion and comparison. When Oldham (1976: 460) first 

 recorded the presence of this species in the English Wealden, he 

 placed it tentatively in the Ginkgoales and remarked: 'this taxon is of 

 ginkgoalean affinity but does not agree specifically with any of the 

 published taxa". However, the single median stomatal band occur- 

 ring in these leaves suggests to us that it is appropriately assigned to 

 the coniferous form-genus Sciadopityoides Sveshnikova. Of course 

 no affinity with the living genus Sciadopitys is inferred and the 

 family affinities of Sciadopityoides greeboana sp. nov. remain un- 

 certain. 



The leaves of S. greeboana are thought to have been spirally 

 arranged on Sulcatocladus shoots which are described as a new 

 species below. Attribution of the leaves of S. greeboana to shoots of 

 Sulcatocladus is based on a constant association of the two species in 

 the English Wealden and the strong similarities of their cuticles. Very 

 similar shoots have been figured by Bose & Manum ( 1990, 199 1 ) in 

 association with Sciadopityoides-Vike leaves from the Lower Creta- 

 ceous of West Greenland, Spitsbergen and Arcfic Canada. 



The leaves of 5. greeboana have many features in common with P. 



linkii: a high frequency of leaves with broken apices; a differentiated 

 midline on the upper epidermis; a tendency for epidermal cells to 

 occur in pairs following late division; stomata which are always 

 longitudinally aligned and restricted to the lower epidermis; guard 

 cells with thickly cutinized, elongate dorsal plates, variably devel- 

 oped polar appendages and sometimes weakly cutinized ventral 

 walls. It seems very likely that the two Wealden conifers belong to 

 the same family. The case for including P. linkii in the Coniferales, 

 possibly the Araucariaceae, has been discussed by Watson & Harrison 

 (1998). The needles of P. linkii differ significantly in only two 

 respects. Firstly, the stomata are arranged in three bands in the basal 

 part of the leaf, although they merge into one broad band in the distal 

 regions. Secondly, P. linkii is known to have several dichotomising 

 veins although veins are not always preserved and their positions are 

 not reflected in the epidermis. Numerous leaves off. linkii had been 

 examined and the species described several times before leaves with 

 veins preserved in them were recognised (Watson & Harrison 1998). 

 The possibility cannot therefore be ignored that S. greeboana might 

 also have had more than one vein, thus reinforcing its affinities with 

 P linkii. 



The reason why almost all the leaves have their tips missing 

 remains a matter under discussion. Apart from P. linkii, similar 

 proportions of leaves with missing tips have been recorded in 

 Sciadopityoides macrophylla (Florin) Sveshnikova from the Jurassic 

 of Norway (Manum 1987), Bilsdalea dura Harris (1979) from the 



