HISTORY OF RESEARCH. 



1 \ \ \ v 



1875. 



Nicholson, II A., 



" On a new Genus and 



some new Species of 



G-raptolites from the 



Skiddaw Slates,'" 'Ann. 



Mag. Nat. Hist.,' 



ser. 4, vol. xvi. 



A now genus of Graptolites, from the Skiddaw slates, was 

 described by Nicholson in 1875, viz. Azygograptus, with its 

 type species A. Lapworthi. This genus, which has but one 

 branch, with the sicula in a similar position to that of 

 Didymograptus, Nicholson considers to be intermediate in its 

 characters between M onograptus Nilssoni and the N&magraptus 

 of Emmons. A new species of Thamnograptus, T. Doveri, 



is named. The specific name Didymog. gibberulus is given to one of the forms 



originally included under Salter's D. caduceus. 



In a joint paper read before the British Association at 



, T . , , JT , 7 Bristol, Nicholson and Lapworth divided the Coniston Mud- 



iV i en olson a n a Lapworth , l 



" On the Central Group stones into two distinct groups, the Skelgill and the Knock 

 of the Silurian Series beds, correlating the former with the Scottish Birkhill beds 

 on account of the similarity of their Graptolites, and the 

 latter with the Gala and Hawick beds. The Coniston Flags 

 are regarded as the equivalents of the Denbighshire Flags 



and the Riccarton Beds. 



In 1875 Mallada gave brief descriptions and figures of 

 some species of Graptolites met with in Spain. These 

 include : (1) Monograpsus Nilssoni, (2) M. latus, (:5) M. Halli, 

 (4) M. Bechi, (5) M. priodon, (6) M. convolutus, (7) Diplograpsus 

 palmeus, and (8) I), pristis. The figures are not original, but 

 copies of those of previous authors. 



Several new species of Graptolites are described by White 

 in the 'Report of the 100th Meridian.' These are: (1) 

 Phyllograptus Loringi (very closely allied to P. typus) from 



Utah, from beds belonging to what he calls the Canadian Period. From beds of 



the Trenton Period he describes (2) Qraptolithus (Glimacograptus) ramulus 



(Dicranograptus), (3) Diplograpsus hypniformis (D. foliaceas), (4) 1). prist is? (5) l>. 



quadrimucronatuti? These occur near Belmont, Nevada. 



The same year Richter recognised two horizons of Grap- 

 tolite shales (a Lower and an Upper) in Thiiringia, but noted 

 that nearly all the forms met with in the lower occur also in 

 the upper. Two new species are figured and described. 

 (1) Dicranograptus posthumus, (2) Monog. microdon, and also 

 (3) Monog. ludensis (= M. Flemingii), (4) M. fugax, (5) 

 Cyrtograptus sp. (G. Murchisoni?). M. Nilssoni is described, 



but not figured. 



The results of Hopkinson's and Hicks' discovery of Graptolites in the 



St. David's district, which had been noted from time to time, were collected and 



published in 1875. 



of the North of Eng- 

 land," ' Brit. Ass. 

 Report.' 



1875. 



Mallada, 



" Sinopsis de las 



E species Fosiles que s< 



han encontrado en 



Espana," ' Boletin de 



la Com. Geol.' 



1875. 

 White, C. A. 



1875. 



Richter, R., 



" Aus dem Thuring- 



ischen Schief ergebirge, ' ' 



' Zeit. d. deutsch. geol. 



Gesell.,' bd. xxvii, 



heft 2. 



