viii BRITISH GRAPTOLITES. 



Gr. Sagittarius, together with three new species of his own, namely, P. pristis, 

 r. folium, and P. convolutus. Three years later he described and figured in his 

 ' Supplementnm secundum ' three additional forms, namely, Fr. geminus, Pr. 

 teretiusculus, and a net-like form. This last was a Didyonema, although he 

 regarded it as the impression of a monocotyledonous plant. All Hisinger's species 

 were classed by him under Nilsson's generic name of Frionotus. 



Ig3() In 1839, Murchison, in his ' Silurian System,' quotes the 



Murchison, views of Dr. Beck, the Danish naturalist, as to the probable 



' The Silurian nature of the Graptolites. He writes, " Very different opinions 



System. have been entertained as to the place which the Graptolites 



hold in the series of living beings, but that of Professor Nilsson may come nearest to 



the truth, who conceives the Graptolite to be a polyparium of the ceratophydian 



family. Yet I am more inclined to regard them as belonging to the group 



FeniiatuliiicV, the Linuc^an Virgulariahemg the nearest form in the present state to 



which they may be compared." Dr. Beck refers to the new names of Priodon 



and Lomatoceras, suggested by Nilsson and Bronn respectively, but considers both 



to be unnecessary. 



Three species of Graptolites are figured in Murchison's ' Silurian System.' The 

 descriptions of two of these are by Beck, namely, those of Graptolithvs ludensis 

 and (t. Murchisoni. The name O. Murrhisonl was given by Beck, but the name 

 G. ludensis was substituted by Murchison for a form previously recognised by him- 

 self, which had been named by Beck in his MSS. Gra])tolitlbUS virgulatus. One of 

 the forms figured as G. ludensis is identical wath Bronn's Monograptus priodon ; the 

 other is rather of the type of M. colonus of Barrande. G. Murchisoni is an example 

 of Didijmograptiis. The third species, G. foliaceus, is a Diplograptus, and is 

 described by Murchison himself. 



Murchison emphasises throughout his work the fact that the range of the Grap- 

 tolites is exclusively Silurian, and he records them as high up in the series as 

 the lower Ludlow shales. 



Quenstedt, in a short paper in the ' Neues Jahrbuch ' in 



Quenstedt, 1840, notices the structure of certain Graptolites. He adopts 



" Ueber die vorziiij;- the views of the older palgeontologists that they belong to the 



lichsteu Keuuzeichen family of the Cephalopoda, and he states that he " does not see 



au 1 pen eues ^^, Nilsson should place them among the sea-pens." But he 

 Jalirb. f. Min.,' / ^ .... 



evidently does not consider that the question of their affinities 



is definitely settled, for he says elsewhere, " A close examination of well-preserved 



specimens might, however, perhaps strengthen the view that they all belong to the 



class of the Foraminifera, and not either to the Cephalopoda or to the corals." 



As regards the structure of the Graptolites, he notes that he has observed 



distinct transverse partition walls, as in the Cephalopoda, but no last chamber. 



He recognises also a siphon running down the back of the shell. He considers 



