Dr. Sans Heck — Fissureless Volcanoes. 59 



a name by which to designate a special kind of cast of a genus known 

 otherwise (compare the Knorria, etc., of Lepidodendron), there appears 

 no reason now to give Benstedtia a generic name of its own. In 

 describing the African plants Professor Seward retained the name 

 Benstedtia, for, as he said (1903, p, 35), " without anatomical 

 evidence ... a non-committal term such as Benstedtia is preferable" 

 to the specific name given to similar things by Fliche, which attributes 

 to them distinct affinities. As, however, we have now direct evidence 

 in the details of the wood tracheids that our British specimens belong 

 to the Coniferse, but are not Araucarian, it seems best to include 

 them in the genus Conifer -ocaulon of Fliche and retain Konig's original 

 specific name Benstedii. Fliche's specimens, although very probably 

 really belonging to the same true species, may be left under Fliche's 

 specific name till his view as to their nature is proved or disproved by 

 evidence of internal structure. Our plant, then, the Dracmia Benstedii 

 of Konig, the Benstedtia sp. of Seward, is best designated by the 

 name Conifer ocaulon Benstedii, and placed among the higher Coniferse. 

 Though the 'Dragon-tree' was a much more romantic figure 

 before its ordinary gymnospermic features were revealed, consolation 

 for this loss may perhaps be afforded by the fact that it illustrates the 

 use that even pulverizing fossil wood may be in determining affinities 

 of doubtful plants, when handled with a method so technically simple 

 as that described above. 



A 



III. — Fissureless Volcanoes. 



By Dr. Hans Beck. 



S I could not give in this paper anything like a full account 

 of my observations and the results of my studies concerning this 

 question made during an expedition through Iceland in the summer of 

 1908, I must refer the reader to my special papers on this subject. 1 

 Everyone will find there the reasons which have induced me first 

 to suppose the independence of the so-called ' Schild ' volcanoes in 

 Iceland of pre-existing fissures. This idea is confirmed by collecting 

 proof after proof on the subject in the field during my researches. 

 Naturally I could not give all the details in a first short preliminary 

 communication, a fact which, I am sorry to say, has caused Professor 

 Schwarz to doubt the correctness of part of my observations and 

 conclusions. I may therefore be allowed to discuss shortly the two 

 main objections of Professor Schwarz to my theory. 2 



Briefly summarized, the facts are as follows : Out of the level 

 highlands of Central Iceland a few block-like, square-formed, flat-topped 



1 Hans Beck, " Ein Beitrag znr Spaltenfrage der Vulkane " : Centralbl. f. 

 Min., Geol., u. Palaeont., 1910, No. 6, pp. 166-9, 1 fig. " Ueber Erbelbungs- 

 kratere": A. d. Monatsberichten d. Deutscben Geol. Ges., Bd. lxii, No. 4, 

 pp. 295-319, 9 figs., 1910. " Islandische Masseneruptionen " : Kokens geol.- 

 palaeontolog. Abbandlungen, Heft ii (Bd. ix der neuen Folge), pp. 80-186, 

 9 plates, 1910. " Das vulkanische Horstgebirge Dyngjuf joll mit den Einbrucbs- 

 kalderen der Askja und des Knebelsees sowie dem Budloffkrater in Zentral- 

 island " : Abbandlungen der Kbnigl. Preuss. Akademie der Wissenscbaften 

 vom Jahre 1910, pp. 1-100, 8 plates. 



2 See Geol. Mag., September, 1910, p. 392. 



