108 Proceedings of the Boy at Physical Society. 



Graptolithus gracilis, or of some similar species." * Three 

 years later the progress of our knowledge of the Graptolites 

 in Britain compelled Hall to recognise the generic distinct- 

 ness of this Graptolithus gracilis; and in the Twentieth 

 Annual Eeport of the State Cabinet of New York, published 

 in 1865, we find Hall placing Gra^ptolithus gracilis and some 

 allied forms in a new generic group designated Cmnogra^tus,f 

 of which he implies that he regards Graptolithus gracilis 

 as forming the type species. In this connection he again 

 very properly calls attention to Emmons's species and genus 

 (p. 236), and distinctly admits the possibility of the generic 

 identity of Nemagraptus and Coenogra;ptus ; but with the 

 reservation that Emmons's remarks regarding the absence 

 of cellules would, if eventually verified, exclude the typical 

 species from that group. This is probably meant to glance 

 at Emmons's second species, Nemagraptiis cajpillaris, which 

 Hall had already more than, once referred to, but without 

 attempting to identify it,| as he held that its relations could 

 scarcely be determined from the figure given. 



The generic distinctness of Hall's Graptolithiis gracilis had 

 already been pointed out by Dr H. A. Mcholson,§ who pro- 

 posed for it the title of Helicograptus, which however he 

 subsequently suppressed on becoming aware of what Hall 

 had done. 



In 1871 Mr Jno. Hopkinson, accepting Hall's suggestion 

 of the probable identity of Nemagraptus elegans, Emm., and 

 Gcenograptus gracilis^ Hall, and carrying out the recognised 

 rules with regard to priority of zoological nomenclature, 

 applied Emmons's generic title of Nemagraptus to the whole 

 of the forms previously included under Coenograptus, Hall, 

 Cladograptus, Carr., and Pleiirograptus, Mch.|| In 1873 

 these special forms and their most intimate allies were classed 

 by myself as forming a distinct family of the Graptolites ; and 

 I laid aside my proposed title of Leptograptidcc for this family 



* Graptolites of the Quebec Group, p. 43. 



+ Loc. cit., p. 236. 



X Graptolites, Quebec Group, p. 43. 



§ Annals and Mag. Nat. Hist., 1868, p. 25. 



il Geological Magazine, vol. viii., p. 5. 



