156 BENNETTITES. 



form ; 1 it may possibly be an inflorescence of some cycad-like 

 stem, but is far from satisfactory. 3 One of the forms figured by 

 Zigno 3 (Blastolepis acuminata] is named by Saporta 4 W. Italica. 

 Dawson's W. recentior is an exceedingly poor specimen and 

 hardly worthy of any name. 



It is difficult in the case of some of the above fossils to 

 precisely define their geological horizon. The Bornholm species, 

 W. Forchhammeri, Nath., 5 is from beds which have recently been 

 shown by Bartholin to contain 46 species of plants, of which 

 25 are regarded as Rhaetic, and about 15 as indicating a Lower 

 Oolitic age. 



The fragment described by Dawson 6 as W. recentior is from 

 the Canadian Middle Creek series, which is compared with the 

 Patoot series of Greenland and the Dakota group of the Western 

 United States. 



The unnamed Wiltiamsonia is from the Kootanie formation, 

 which is correlated with the Neocomian of Europe. 7 



Fontaine's Potomac series includes rocks differing somewhat 

 widely in age, Jurassic and Cretaceous strata being incorporated 

 in one formation. 



Wittiamsonia ? Riesii is probably a true WilUamsonia with 

 numerous and unusually narrow bracts ; the author of the species 

 compares it with some composite flower. 



As regards the Indian beds, it has long been a difficult problem 

 to determine their exact geological position; the Rajmahal beds 

 are spoken of by Oldham, 8 in the recent edition of the Manual 

 of Indian Geology, as Liassic, the Kach (Cutch) or Umia beds 

 being correlated with the Upper Oolite, but the precise horizon 

 can only be approximately stated. 



1 Saporta, Pal. Fran9_ vol. iv. p. 118. 



3 Heer, Flor. foss. Arct. vol. vi. p. 59, pi. xii. fig. 1; pi. xiii. fig. 9. 

 [Since writing the above I have examined Heer's type specimen of W. cn-tacea 

 in the Geological Museum in Copenhagen, and find the impression is very 

 indistinct and unsatisfactory.] 



3 Zigno, loc. cit. p. 173, pi. xlii. fig. 10. 



4 Saporta, loc. cit. p. 180, pi. ccli. fig. 3 ; and pi. cclii. fig. 4. 



5 Nathorst (4). See also Bartholin, p. 112. 



6 Dawson (A. 5), p. 12, pi. iv. fig. 1. 



7 Dawson (2), p. 87. 



8 Medlicott and Blanford, p. 207. 



