260 REPORl ON THE STATE CABINET. 



The following is a list of the species of American Graptolites which have 

 a single seiies of cellules on one side of the stipes or branches, indicating 

 their relation to the point of origin or initial point, so far as known, fol- 

 lowing the arrangement of the synoptical table, page 251. 



Genus Geaptolithus, Linnagus. 



A. Species known only as sisiplb and single stipes from their origin. 



{Monoprion Monograptus, etc.) 



G. clintoni. 



B. Species having a bilateral arrangement of parts ; often numerously 



sub-divided. (Sub-genus Monoprion, Barrande; Monograptus, Geiiiitz; 



DiDYMOGEAPTUS, M'Coj.) 



a. Polypaiy consisting of two stipes from a single initial point, with the 



cellules on the upper or inner side. (Didymograptus, M'Coy, in part; 

 Cladograptus, Geinitz, in part.) 



G. {-D.) arcuatus, G. extenuatus, ' G. pennalulus, 

 bifidus, Jlaccidus, serralulus, 



constrictus, indentus, similis, 



divaricatus, nitidus, tenuis, 



extensus, 



b. Polypary consisting of four simple stipes from a single axis, with or 



without a central disc. (Tetragraptus, Salter ; Dichogeaptus, Salter, 

 in part.) 



G. alatus (disc), G. crucifer (disc), G. headi (disc), 



bigsbyi, dentiaulatus, quadribracliiatus. 



bryonoides, fmticosus, 



c. Polypary consisting of eight simple stipes proceeding from a single axis, 



with or without a central disc. (Dichograptus, Salter, in part.) 



G. odobrachiatus (disc), G. octonarius. 



d. Polypary consisting of more than eight simple stipes (stipes not divided 



after becoming celluliferous), proceeding from a single axis, with a dis- 

 tinct broad, corneous disc. (Dichograptus, Salter, in part; Logano- 

 GRAPTUS, Hall.) 



G. logani, G. logani, var. 



It may be found desirable to include under the latter term G. octobrachiatus, 

 G. alatus, G. crucife/)' and G. headi, on account of the presence of a central disc. 



