OF CBETACEOUS PLANTS. '2o7 



LitJiotJuimmum ramosisslrnum," but he wrote before the more 

 detailed measurements and study of the fossils had been under- 

 taken. Seward ( 1 898) gives some of Rothpletz's figures and 

 describes Z. mamiUosum, Giimbel, in his more recent Text- 

 book. 



Litliotliamnium has not hitherto been recognised in British 

 Cretaceous rooks, although it is so wideljf spread in European 

 deposits of the same age. Though no specimens have been 

 identified in the British Museum Collection, I have had the 

 privilege of examining Prof. Eothpletz's original specimens in 

 Munich. In several of these slides the internal structure is 

 remarkably clear, and there appear to be several true species 

 among those described from the Cretaceous, even if all the 

 eleven species are not really distinct. 



Test-fig. 11. — Lithoth/uniiiiLiii manuUosicm, Gijmbi-'l, to thow external 

 features. Nat. size. After Giiiiibel. 



Iiithothamniuin mamillosum, Giimbel. 



1871. Lithothamniwn viainiUosum, Giimbel, Abhandl. k. Akad. 



Wis:f. MiincheD, vol. 11, p. 41, pi. ii, figs. T a, 7 h. 

 1891. Lithothamnium onatniUosuin, Eothpletz, Zeitschr. deutsch. 



geol. Ges., vol. 43, p. 315, pi. xvii, fig. 7. 

 1898. Lithothamnmm mamillusum, Seward, Fossil Plants, p. 188, 



text-fig. 32 A, p. 1.j5. 



Algal thallus irregularl}' branched, nodidar and crust-like, 

 the branches about 5 mm. long and 4-5 mm. thick. In micro- 

 scopic section the individual cells of the perithallium are 

 5'5-8 fx in diameter and of square outline, and of the 

 hypothallium about 18 fi in length. 



Apparently sterile. 



As text-fig. 11 shows, this irregular coralline mass may well 

 have been mistaken for an animal nullipore. Previous to 



s 



