G. B. Wieland — Williamsonian Tribe. 447 



anastomosely netted forms, a series which so far baffles resolu- 

 tion with respect to time. Though surely a transition from . 

 the old Cycadofilicalean alliance with tri- and even (juadri pin- 

 nate fronds to the Cycadaeere and also to net-veined leaves, 

 must be somewhere involved in the origins of the types already 

 known. It is plainly the more stereotyped cycad and conifer- 

 ous genera that now survive; in both groups the sameness of 

 foliage is but the expression of stability, and wholly deceptive 

 when we try to picture the certainly more varied foliage in 

 earlier and plastic stages or lesser plastic groups of these gym- 

 nosperm lines. But even so, in a species of Zamia found 

 growing near the Pacific coast in Southern Oaxaca, the writer 

 has noted a strongly dichotomous venation give rise to a sparse 

 false netting. And the gap between such a form and the long 

 mesh net-veined cycad Dictyozamites is not so -great, nor yet 

 that between the latter form and a true type of mesh netting, 

 such as we see in presumably archaic dicotyledonous forms like 

 Cissites and Vitiphyllum, and in Liriodendropsis ; or again 

 in Gnetum gnemon. Nor is it unreasonable to infer a transi- 

 tion from a frond with few pinnules, as in the Oaxacan Zamia 

 just cited, to a single blade, whether in the case of parallel or 

 net-veined types. While it may prove fully significant that 

 not once amongst the great Permian series of Ginkgo leaf 

 types does a transition from dichotomous to netted venation 

 occur, but exactly amongst the cycads as characterized by yet 

 other definitely proangiosperraous features. 



Ovulate Cones and Buds. (Figures 6-15.) 



The discovery of the Williamsonian tribe began, as already 

 recalled, early in the last century with the collection of the 

 sightly buds, ovulate fruits, disks and leaves of Williamsonia 

 gigas, found intermingled with an abundance of fossil plants 

 along the eroded cliffs of the Yorkshire coast. Here William- 

 son and his father, as well as other local collectors, diligently 

 sought out the handsome series of Cycadophytean fruits, which 

 mostly found their way into the Williamson collections, those 

 of the Jermyn Street Museum, of Cambridge, and the James 

 Yates collection already specially alluded to in the introduc- 

 tory paragraphs.* But it appeal's that the partly indiscrimi- 



* Williamson says that his father first drew attention in 1832 to some fine 

 specimens he had just discovered at Hawkser, hoth visiting the locality in 

 1833 (4). But in this connection it should be remarked that the first Cycade- 

 oidean or Williamsonian fruit ever figured appears to have been Buckland's 

 Podocarya of 1836' (la) from the "lower region of the inferior oolite" on 

 the E. of Charmouth, Dorset, which is on the coast near Lyme Regis. 



This fossil may also have been collected earlier than 1833, and the failure 

 of the locality to yield other recorded specimens is only less to be lamented 

 than the loss of the original ; for a close study of the figures of Buckland as 



