THE GRAPTOLITES. 367 



concerning the morphology and phylogeny of the graptoli- 

 toidea. It would serve no useful purpose to give details of 

 the numerous papers which confirm the value of the grap- 

 tolites for purposes of correlation of the strata. In Britain, 

 Lapworth himself has described a number of graptolitic 

 bands interstratified with deposits containing the remains of 

 other organisms in Ayrshire (16). Much remains to be 

 done in this respect, for in order to utilise to the utmost the 

 value of these organisms as stratigraphical indices, it will be 

 necessary to have a complete correlation of graptolitiferous 

 strata of all ages, with those which contain these organisms 

 rarely or not at all. For this purpose all graptolites should 

 be carefully collected and preserved from out of those 

 deposits in which they are not frequent, and are associated 

 with other organisms. They should be looked for especi- 

 ally in calcareous deposits, for as we have already seen, such 

 specimens are particularly valuable as furnishing information 

 concerning the morphology of these fossils. The southern 

 uplands of Scotland have recently been re-examined by the 

 geological surveyors, and it is scarcely necessary to state 

 that they have fully confirmed Professor Lapworth's classifi- 

 cation of the Lower Palaeozoic Rocks of this region. In 

 England Professor Nicholson and the present writer have 

 defined graptolitic zones in the Skiddaw Slates, Llandovery, 

 Tarannon, Wenlock and Lower Ludlow Beds (17). Messrs. 

 Lake and Groom have detected the Monograptus gregarius 

 zone of the Birkhill shales and zones of Monograptus per- 

 sonalis, M. Flemingii, M. colonius and M. leint wardinensis 

 near Corwen and Llangollen (18), whilst in a paper which 

 has hitherto only appeared in abstract, Miss Wood and 

 Miss Elles have detected several zones of the Birkhill-Gala 

 beds near Conway. On the Welsh borderland W. W. 

 Watts has found one graptolitic zone of Wenlock and two 

 of Lower Ludlow age on the Long Mountain (19). In 

 addition to this, various other graptolitic zones have been 

 detected in different parts of Great Britain, and the zones of 

 the Moffat area have been traced into Ireland. On the 

 European continent, Linnarsson, Brogger, Tornquist, 



Tullberg and others have detected numerous graptolite 



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