STUDY OF THE GRAPTOLITES. 261 



e. Polypaiy with the stipes proceeding from a single axis, and more or less 

 frequently branched during their entire length; not known to have a 

 central disc. (Dichogeaptus, Salter, typical forms). 



G. abnormis, G. multifascmtus, G. nchardsoni, 



Jleodlts, ramuhis, rigidus. 



milesi, 



f. Polypary developed from an initial point in two or more directions; these 



divisions developing celluliferous branches, and themselves becoming 

 celluliferous towards their extremities. (Cladogeaftus [?] CaiTuthers ; 



CCENOGEAPTUS, Hall.) 



G. gracilis, G. divergens, G. surculans. 



g. Polypary consisting of two simple stipes from an initial point, with a 



single range of cellules on the outer margin of each; or, with the stipes 

 simple for a short distance above their origin with a double range of 

 cellules, and bifuracting above with a single range on each division. 

 (DiDTMOGRAPTus, M'Coy, in part; Cladogeaftus, Geinitz, in part=DiCEA. 

 NOGEAPTUS, Hall.) 



G. arundinaceiis, G.furcatus, G. sextans, 



divancalus, ramosas, 



It vrill be seen that the G. clintoni of the Clinton group is the only 

 known American species of Graptolite of the monoprionidian type in 

 which we have not demonstrated a more or less compound structure. It 

 is possible that this species may grow in simple hnear stipes as repre- 

 sented in some of the European species ; but if this should be proved 

 regarding it, such a character, taken in connection with the peculiar 

 form of cellules, would entitle it to rank as a sub-genus at least, for which 

 I would suggest the name, Lagenograptus. 



