ixii 



BRITISH GBAPTOLITES. 



1868. 



Nicholson, 



" On the Graptolites 



of the Coniston Flags 



with Notes on the 



British Species of the 



Genus Graptolites," 



' Quart. Journ. Geol. 



Soc.,' vol. xxiv. 



Geinifzianus, and 



Nicholson's second paper was entitled " On the Graptolites 

 of the Coniston Flags." This also is almost entirely descrip- 

 tive, twenty-four species of Graptolites being described, of 

 which five are new. 



The following are the genera and species noticed in 

 this paper: (1) Diplugrapsus folium, (2) l>. palmeus, (3) 

 D. an gastif alius, (4) V. putillus, 1*. vesiculasus, D. pristis, and 

 two new Dvplograpti (5) D. tamariscus and (6) l>. con- 

 fertus ; (7) Glimacograpsiis teretiusculus ; (8) Betiilites 

 a new form (9) B. perlatus ; (10) lit strife* peregrinus, 

 and (11) B. Linnsd ; (12) Gmptolithus lobiferus, (13) var. Nicoli and (14) var. 

 exiguus, (15) Gr. Sedgwiclcii, (16) var. triangulatus and (17) var. spinigerus, 

 (18) Gr. fimbriatus, (19) Gr. NiUsoni, (20) var. major and (21) var. minor, (22) 

 Gr. tenuis, (23) Gr. bohemicus, (24) Gr. priodon, (25) Gr. colonns, (26) Gr. 

 Sagittarius, (27) Gr. turriculatus, and a new form, (28) Gr. discretus, of which 

 Nicholson remarks that "the long sub-mucronate extremities of the cellules are 

 often furnished with little ovoid, or triangular, vesicular bodies depending from 

 their apices." 



It is impossible to discuss the identification of each species in detail, but in the 

 light of our present-day knowledge we are aware that several of the forms assigned 

 by him to species already named must be regarded as incorrectly referred. The 

 paper added very greatly to the number of British Graptolites and to our know- 

 ledge of the Graptolite species occurring in the higher beds of the Lake District. 



As regards the age of the Coniston Flags, Nicholson considers them to be 

 Lower Silurian, and the term as applied by him included all the beds between the 

 summit of the Coniston Limestone proper and the base of the Coniston Grits. 



The four remaining papers by Nicholson Avere published in 

 1868 in the 'Annals and Magazine of Natural History.' The 

 third, entitled " On the Nature and Zoological Position of the 

 Graptolitidae," gives a clear account of the general state 

 of knowledge at that time with respect to the morphology, 

 zoological affinities, etc., of the Group. 



Treating of the morphology of the Graptolites, Nicholson 

 discusses in turn the " three factors, structurally and develop- 

 mentally distinct," of which each single linear stipe is composed — i.e. (1) the solid 

 axis, (2) the common canal, and (3) the cellules. 



Soliil axis. — In Monoprions this is a solid cylindrical rod, but in Diprions it is 

 " certainly a corneous plate dividing the frond into two vertical compartments, 

 apparently composed of two lamina?, with a median cylindrical rod and perhaps 

 including a central dotal." The proximal extension of the axis is probably 

 present in all true Graptolites, and constitutes the " radicle " or " initial point " of 



1868. 



Nicholson, 



" On the Nature ami 



Zoological Position of 



the Glraptolitidse," 



' Ann. and Mag. of 



Nat. Hist.,' ser. 4, 



vol. i. 



