HISTORY OF RESEARCH. xrv 



The peculiar structure presented by the curious forms (25) J>. tricmwis, l>. 

 marcidus, and D. JEtheridgii is described aud explained, the new generic title 

 Cryptograptus is suggested for them, and a new variety (26) var. Schaferi is 

 figured. 



A new species of Lasiograptus, (27) L. retusus is figured and described. 



In a paper giving the results of his personal researches 



• among the Pro-Devonian Rocks of Bohemia, Marr shows that 



„„ ,, _ ' . the Band E. e. 1 of Barrande includes three distinct Graptolitic 



"On the 1 re- Devonian l 



Eocks of Bohemia," zones (1, Viplograptus zone; 2,priodon zone; 3, colonus zone), 

 ' Quart. Journ. Geo]. and that the same three zones occur in the so-called "colonies" 

 Soc,' vol. xxxvi. i n t,] ie same order, thus affording "grounds for the supposi- 



tion that these are only portions of the Band E. e. 1 faulted 

 down among the grits and shales at the summit of the Cambrian (Ordovician) 

 Series." 



During the years 1879 — 1880 appeared Lap worth's paper 



Lavworlh " ^ n ^ ie Geological Distribution of the Rhabdophora," 



•' On the Geological which was published in parts in the 'Annals and Magazine of 



Distribution Natural History.' 



of the Rhabdophora, This memoir is devoted to an exhaustive examination and 



' °' , discussion of the available facts bearing upon the distribution 



Hist,, ser. 5, vols. ° l 



iii iv v ami vi an0 - vertical range of all the known Graptolite species in 



Britain and abroad, with a view of correcting the prevalent 



neglect of these fossils by geologists in general and of showing their importance 



as constituting probably the most reliable chronological indices available in 



working out the detailed stratigraphy of the Lower Palaeozoic formations. 



Part I. — Historical. — In the introductory part Lap worth points out and illus- 

 trates the geological and palasontological difficulties which had caused these fossils 

 to fall into disrepute, enters into a critical discussion of previous opinions, and 

 summarises the latest views upon the subject. 



Part II. — Data. — The second part of the work is devoted to the fixation of 

 tin; actual localities and horizons in Britain and abroad from which known species 

 of Graptolites had been obtained, so far as could be gathered from previous publi- 

 cations and personal researches, and the special association of forms is given in 

 each case. 



Part III. — Results. — In the third part the results deductible from t he foregoing 

 data, are discussed and tabulated both from the strati graphical and the palseonto- 

 graphical points of view. In the geological section the fauna of each Graptolite- 

 bearing formation is fixed, and in the palseontological section each Graptolite 

 family is d,ealt with and the ranges of the component genera and species deduced 

 and shown in illustrative Tables. 



Part IV.— Conclusions. In the fourth part Lapwortb points out thai strati- 



