HISTORY OF RESEARCH. cxlvii 



are afterwards shown (with the addition of a fifth zone) to hold in the main in the 

 Builth District and Long Mountain area of the Welsh Borderland. Brief notes 

 are also given of the Ludlow graptolitic fauna in the Dee Valley, the Lake 

 District, South Scotland, Dudley, and the Abberley Hills. 



Description of Species. — The following species, which had been already named 

 by previous observers, are re-described and re-figured : 



Group I. — M. dubius, M. tumescens var. minor, M. gotlandicus, M. ultimus. 



Group II. — M. colonus var. ludensis, M. Boemeri. 



Group III. — M. chimsera var. Salweyi, M. leintwardinensis. 



Group IV. — M. uncinatus var. micropbma. 



Group V. — M. scanicus. 



Group VI. — Gothograptus nassa, M. Nilssoni, M. bohemicus. 



The following new species are figured and described : ill. vulgaris, var. a, var. 

 b, M. tumescens, M. comis, M. colonus var. compactus, M. varians, var. a, var. b, 

 var. pumilus, M. chimsera var. a, M. leintwardinensis var. incipiens, M. nncinatus 

 var. orbatus, M. crinitus, Betiolites spinosus. 



1900. 



Lajnvorth, H., j^ ^[ Y( [ p a p er f especial stratigraphical importance 



" The Silurian Sequence . 



f Eh I " 'O -t was P u fr usne( i during this year by H. Lapworth on the 



Journ. Geol. Soc. ' "Silurian Sequence of Rhayader." 



vol. lvi. 



He shows that in the district of Rhayader there occur representatives of all the 



Llandovery-Birkhill Graptolitic zones as well as of the Tarannon ; these zones are 



mapped by him in detail. 



He describes and figures three new species : Glimacograptus parvulus, G. 



extremus, and Diplograptus magnus, and gives a description of Diplog. modestus, 



which had previously been figured only. 



1900. In the year 1900 Hall published the results of his exami- 

 HaJl, T. S., nation of a collection of Graptolites made by Mr. E. F. 



" 0l1 a Collection of pitman from Mandurama. 



Grraptolites from TT ni -, •-, -, n ,-, o -\ ■ ^ ^ • i 



,, , r „ „ , Hall describes and figures three forms which he considers 



Mandurama, 'Records 



Geol Survey N S are new > ^ u ^ on ty names two, namely, Glimacograptus affinis 

 Wales,' vol. vii, pt. 1. and Diplograptus manduramae. 



,„_ In 1901 Newton described and figured a slab of Grapto- 



1901. ° . x 

 N elvton lites collected by Mr. Jessop from the province of Carabaya, 



" Note on Graptolites Peru. The species to which these belong is uncertain, but 



from Peru," 'Geol. they closely resemble Diplograptus truncatus, Lapw. They 



Mag.,' dec 4, vol. vm, are « mc [i ca ti V e of beds near the uppermost part of the 



Lower Silurian." 



In the year 1901 Tornquist published the results of his researches on 



the Phtjllo-Tetragraptus beds of Scania and Vestrogothland, and recognised 



