51 Perner & Kodym — -Zonal Division and 



included three species confined to different, vertically 

 widely separated horizons. Consequently correct identifi- 

 cations could not be made until such a revision had been 

 finished, and this explains not only the quite erroneous 

 assertions of Wenzel as to the non-existence of zones in 

 the Silurian of Bohemia, but also the incongruous views 

 on graptolitic zones in Bohemia held by other authors. 

 In addition, a more detailed division and comparison of 

 Bohemian strata could not be systematically worked out 

 until this revision of species had been made. After 

 redefining the world-widely distributed species of Bar- 

 rande in accordance with his type specimens, I was able 

 to ascertain in the Silurian beds E 1? E 2 , and F x many new 

 species, and to note the presence of forty forms heretofore 

 known only from Great Britain and Scandinavia. Addi- 

 tional studies regarding the vertical distribution of other 

 fossils and different facies in the beds named above have 

 led to results here communicated. 6 



The limit between the Upper Ordovician (Barrande's 

 Bande D 5 ) and the Lowest Silurian beds in central 

 Bohemia is a very sharp one, both from the petrographic 

 and the paleontologic standpoint. The lowest Silurian 

 beds, black graptolitic shales of E 1? rest at some rare local- 

 ities with a slight unconformity on the soft yellow or 

 olive-green, sometimes argillaceous, shales of D 5 , which 

 are interstratified, especially toward the top, with quartz- 

 ites, gritty shales, and graywackes. The fauna of D 5 is 

 also completely different from that in E, having no species 

 in common, and being characterized by Trinucleus, Remo- 

 pleurides, Carmon, Dindymene, Homalonotus, 2Eglina, 

 Asaplius, Agnostus, Areia, and Dicellograptus, as against 

 the Ej shales bearing Diplograptus, Rastrites, and Mono- 

 graptus, so that a hiatus seems to be evident between the 

 Ordovician and Silurian in Bohemia. 



6 It was my intention immediately after the completion of my paleontolog- 

 ical studies on Bohemian graptolites to publish as their final part a paper 

 dealing with the zonal division of the graptolitic rocks of Bohemia. But 

 my official duties connected with the Bohemian Museum and with working out 

 the Gastropoda of Barrande prevented my doing this before the outbreak of 

 the Great War. During the past few years I have been greatly aided by my 

 pupil, Mr. Od. Kodym, with whose collaboration a preliminary report on this 

 subject was published in the Journal of the Bohemian Museum for 1919 (in the 

 Czech language)' In the present English communication I hope to enable 

 foreign workers to get the review and comparison of the Bohemian Silurian 

 beds before the more detailed paper on this subject appears, since I have 

 no idea when this latter can be accomplished, because of the desolate situa- 

 tion of the scientific institutions of Czekoslovakia. 



