STUDY OF THE GRAPTOLITES. 265 



1848. Rev. Prof. Sedgwick announced the occurrence of Graptolitlms 

 Sagittarius, Hisinger, and G. latus, M'Coy in the Skiddaw slates. {Quar- 

 terlij Jour. Geol. Soc, Vol. iv, p. 223). 



1848. J. W. Salter, described G. folium, G. pristis, Hisinger, G. 

 pristis, var. foliaceus, Portlock, G. ramosus, Hall, G. tcenia, Sowerby 

 and Salter, G. tenuis, Portlock, and G. sextans. Hall, from the slates of 

 Loch Ryan, etc. (Quart. Jour. Geol. Soc, Vol. v, pp. 15-17). 



1848. Prof. Phillips enumerated the G. ludensis, G. murchisoni, and 

 three other species in the Builth, Llandeilo, and Harverford-west districts 

 {Memoirs of Geol. Survey, Vol. ii, part 1, p. 308). 



1849. James Nicol enumerated and described Graptolithus griestonensis , 

 G. convolutus, G. ludensis, and G. laxus {Quarterlg Jour. Geol. Soc, Vol. vi, 

 pp. 63 and 64). 



1849. J. Hall stated the occurrence of twenty species of graptolites 

 in the Lower Silurian rocks ; two other species having been found in the 

 Clinton formation* {Proceedings of the Am.er. Assoc, for the Advancement of 

 Science, 1849, p. 351). 



1850. J. Barrande published a memoir upon the graptolites of Bohe- 

 mia, describing seventeen species of Graptolithus, of which fifteen were 

 new ; a new genus, Rastrites, with four species ; and the genus Retio- 

 LiTES, with one species. These are all placed among the Polypi. All of 

 these species, except one, are found in the Upper Silurian ; four of them 

 occur in the colonies of the inferior division, and pass upward to the 

 superior beds ; while one species is restricted to the lower division. M. 

 Barrande has given in this memoir a resume of the geographical and 

 geological distribution of the graptolites in the different countries of the 

 globe. 



1850. Prof M'CoY described three species of graptolites, proposing 

 the name Diplograpsus for those with a double series of cellules. He 

 proposed also the generic name Protovirgularia for a zoophyte which he 

 refers to the Gorgoniadae, but which may perhaps belong to the Graptoli- 

 tidee {Annals and Magazine of Nat. Hist., Vol. vi, 2d series, pp. 270-272). 



1850. Prof Harkness described the graptolites ibund in the black 

 shales of Dumfriesshire, recognizing two species of Rastrites, and ten 

 species of Graptolites {Quar. Jour. Geol. Soc, Vol. vii, pp. 59-65, Plate i). 



1851. Prof M'CoY published descriptions and figures of graptolites 

 from British palasozoic rocks, adopting the name Diplggraptus for the 



* This number of twenty species included some forms known, but not at that time described. 

 Cab. Nat. 34 



