WILLIAMSONIA. 193 



peeten. Mon-is defined Ptilophyllum as follows : " Fronds pinnate, 

 pinnse closely approximated, linear, lanceolate, more or less 

 elongate, imbricate at tlie base, attached obliquely ; base semi- 

 circular or rounded ; veins equal, slender, parallel." ^ In this 

 diagnosis there is nothing to justify a s,eparation from the type 

 represented by WilUamsonia peoten. I have no hesitation in 

 expressing the opinion that there is practically no difEerence 

 between such fronds as Ptilophyllum cutchense, Morr., P. tenerrimum, 

 Feist., P. acutifolium, Morr., and Williamsonia peoten. 



A careful examination of Morris' type-specimen of Ptilophyllum 

 cutchense (in the Museum of the Geological Society of London), 

 and of several other Indian specimens in the British Museum, has 

 convinced me that a generic separation of the Indian and European 

 fossils serves to mislead and indicates a distinction which does 

 not exist. It is by no means certain that the two sets of fossils 

 are specifically identical ; probably they are not, but there is at 

 least no difEerence worthy of generic rank. In several instances 

 there has been a tendency to exaggerate the difEerence between 

 the Grondwana floras and the floras of corresponding age in Europe. 



The occurrence of Williamsonia flowers in the Indian beds, and 

 the existence of Cycadean stems like that shown in Text-fig. 30, 

 demonsti'ate the close correspondence, as regards some members 

 of the Cycadales, between Indian and European plants during 

 the Mesozoic period. The specimen shown in Text-fig. 30 is of 

 interest as affording an example of a stem from India, which 

 presents a very close agreement with a typical Cycadean trunk. 

 The surface of the trunk (A) is covered with persistent leaf-bases, 

 to which fronds of the type Ptilophyllum cutchense were attached ; 

 in a section of the stem (B) a large pith is seen to occupy the axial 

 region, and this is surrounded by a zone of secondary wood, which 

 appears to diffler from the characteristic wood of existing Cycads 

 in having a more compact structure. The broad parenchymatous 

 medullary-rays form a striking feature in the wood of a recent 

 Cycad, but in the Indian stem, so far as it is possible to examine 

 the structure in detail, the medullary-rays are narrow, and more 

 like those of Conifers than Cycads. The lozenge-shaped areas 



' Morris, in Grant (40). 



