HISTORY OF RESEARCH. clxv 



Under the collective title of Didymograptus Ski Her, 



Westerqard A H Westergard includes the Lower and shalier division of 



" Studier ofver Dicho- Angelin's Oerdtopyge Region in contradistinction to the more 



graptus Skiffern in compact and calcareous Upper Division, embracing the 



Skane, etc., ' Lund s Slmmardia beds and Geratopyge Kalk proper, the Upper 

 Geol.Fiiltklubb.,' ser.B, T -,. . . , . ,. . . . , n '„' ,, , ,, . ,. 



, „. , . Division being distinguished further by a fauna consisting 



no. 4, pp. 1-79, pis. i-v. . . . . . 



mainly of Trilobites and Bracliiopods, while the Lower 



Division under description is marked by the presence of Graptolites. The present 

 paper summarises the main facts and conclusions respecting the strata of this 

 Lower Division, regarded by Scandinavian geologists as the basal member of the 

 Swedish Ordovician, and of the beds which are in immediate contact with the sub- 

 formation above and below. The memoir is introduced by a full bibliography of 

 the history of previous research, followed by a detailed account of the results 

 of the author's personal field-studies of the succession in Scania, Westergotland, 

 Ostergotland, Oland, etc. 



The author arranges the strata of the Dictyograptus Skiff er in three sub-zones, 

 characterised respectively by: (1) Dictyograptus fldbelliformis (Eichw.). (2) Idem 

 Forma typica. (2) Clonograptus tenellus (Linnrs.). (3) Dictyograptus fldbelliformis 

 var. Norvegica (Kjerulf.). 



All the known fossils, so far as they are represented in the Lund Museum, are 

 described in the body of the paper, and figured in the accompanying plates. 



Especial attention is devoted to the Graptolites present. Nine distinct species 

 and varieties are recognised. Two of these are noted as new, Dictyograptus 

 fldbelliformis (Eichw.) var. confertus (Linn. MS.) and Clonograptus tenellus (Linn.) 

 var. grandis. All the Graptolite forms noted are admirably figured in the plates, 

 some from striking photographs by Professor Moberg, and others from drawings 

 by Mauda Broman and the author. 



As respects that large group of Graptolites generally united by palaeontologists 

 under the common generic title of Dictyonema, Hall, Westergard expresses his 

 opinion that the group is separable into two distinct sections or genera: (1) a 

 section typified by Dictyonema flabelliforme (Eichw.), and (2) a section typified by 

 Dictyonema cervicome (Holm.), etc. To the first of these sections he restricts the 

 generic title, Dictyograptus (Hopkinson and Lapw.), and for the second he proposes 

 a new generic title — Dictyodendron. Dictyograptus he assigns to the Graptoloidea 

 and Dictyodendron to the Dendroidea. 



A description of the detailed results of the authoress' 



-ay] q L study of the lithological and palseontological succession in the 



" Ordovician and rocks of the Conway District, ranging from the Llandeilian 



Silurian Rocks of to Middle Wenlockian. Particular attention is paid to the 



Conway," ' Quart. Graptolites, some fourteen separate zones being recognised 



Journ. Geo . hoc, an( ^ namec j an( j paralleled with their equivalents elsewhere 



vol. lxv, pp. 169-194. ./,-«.. 



in Or eat Britain. 



