XLVIl] SPHESTOLEPIDIUM 363 



SPHENOLEPIDIUM. Heer. 



Heer 1 instituted Sphenolepidium in place of Sphenolepis, pro- 

 posed by Schenk 2 for Wealden Coniferous branches, because of the 

 previous use of the latter name by Agassiz for a genus of fishes. 

 Berry 3 has recently reverted to the original form Sphenolepis on 

 the ground that its employment by zoologists is not a serious 

 objection. Schenk's definition of his genus includes both vegetative 

 organs and cones, but it is desirable that the name Sphenolepidium 

 should be restricted to fertile specimens or at least to specimens 

 which can with reasonable certainty be connected with cone- 

 bearing examples. The habit of the foliage-shoots of the two best- 

 known Wealden and Low T er Cretaceous species, S. Sternbergianum 

 and S. Kurrianum, is of the type which leads authors to employ 

 such generic terms as Sequoia, Athrotaxites or Athrotaxopsis, 

 Widdringtonites, Glyptostrobus, Araucarites, and Cyparissidium, but 

 in the absence of cones it is impossible to feel confidence in any 

 attempts to distribute such sterile specimens among genera which 

 are characterised not only by a certain form of foliage-shoot but 

 also by a particular type of cone. 



The generic name Sphenolepidium should be retained only for 

 specimens with small, more or less globose, cones possessing spirally 

 disposed cone-scales, cuneate, relatively broad and fairly thick. 

 The cones are much smaller and have relatively broader and 

 thicker scales than those of Elatides though there is no essential 

 difference in the vegetative characters of the two genera. No cones 

 have been described throwing any light on the affinity of the genus 

 and like many others it must be left for the present in the category 

 of Coniferae incertae sedis. The leaves are spirally disposed on the 

 comparatively slender branches and are either ovate, triangular, 

 and free only in the acuminate region, or longer and more spreading 

 and falcate; the latter type agrees with Pagiophyllum while some 

 forms bearing Sphenolepidium cones are rather of the Brachyphyl- 

 lum type. Many of the specimens recorded as Sphenolepidium 

 afford no evidence as to the nature of the cones and should be 

 assigned to Pagiophyllum or Brachyphyttum. The genus is charac- 

 teristic of Wealden or Lower Cretaceous strata and is represented 

 in several European districts and in North America. 



1 Heer (81) p. 19. 2 Schenk (71) B. p. 243. 3 Berry (114) p. 290. 



