. a new Genus of GraptoUtes, 



25 



tive characters of these two Graptolites demonstrates at once, 

 as shown by the annexed diagrammatic sketches, the follow- 

 ing fundamental differences : — Pleurograpsus is distinguished 

 by the total absence of anything like a "funicle," by the 

 " in-egular " manner in which the branches are given off from 

 opposite sides of the main celluliferous stipes, and by the pre- 

 sence of secondary branches. HelicograpsuSj on the other 

 hand, is characterized by the possession of a long and remark- 

 ably distinct funicle, by the regular and definite plan upon 

 which the branches are given off, and by the absence of se- 

 condary offsets. 



Fig. 1. 



Fig. 2. 



Fig. 1. Sketch of Helicograpsiis gracilis, Hall, sp.: a, radicle ; b, funicle. 

 Fig. 2. Sketch oi Pleurograpsus linearis, Carr., sp. 



As the above-mentioned distinctions are as broad and as 

 weighty as those which separate an^ of the genera of the 

 Graptolitidse from each other, there can be no hesitation in 

 following the usual rule in the case of Pleurograj)sus and 

 Helicograpsus. 



Hitherto one Graptolite only has been discovered which can 



