646 NEW YORK STATE MUSEUM 



The Tetraprionidae (Phyllograptus) have been shown to be only an 

 aberrant branch of the Dichograptidae in which the four recumbent branches 

 coalesce. 



Wiman has, in his paper " Ueber die Graptoliten " [p,25jBE] applied the 

 results of his researches to an improvement of Lap worth's system He 

 divides the graptolites into three groups, viz Graptoloidea Lapworth, 

 Metioloidea Lapworth and Dendroidea Nicholson. LTnder these are arranged 

 the families and genera, which are largely taken from Lapworth's " Improved 

 Classification of the Rhabdophora." In this way he has placed later erected 

 genera in their respective places, adding however, that in his belief many 

 of them, notably among the Dichograptidae, are not deserving of generic 

 rank. 



A greatly differing system has been proposed by Freeh [1897, p.568ffj. 

 This author has, in recognition of the important fact, that all the later 

 graptolites have a virgula incorporated into the rhabdosomes and bear the 

 sicula at the distal end of the rhabdosomes, divided all graptolites into two 

 orders, viz the AxonoUpa, or forms without an axis, and the Axonophora, or 

 forms with an axis. The Axonolipa contain the families Dendrograptidi 

 (Dictyonema, Dendrograptus etc.) and Diehograptidi (including Dicho- 

 graptidae Lapw., Leptograptidae Lapw., Didymograptidae auct. and Phyllo- 

 graptidae Lapw.). The latter are again divided into the subfamilies 

 Didymograptini, Tetragraptini and Phyllograptini. The Axonophora are 

 subdivided into the families Climacograptidi, Diplograptidi, Monograptidi 

 and Retiolitidi. The Climacograptidi, hitherto united with the Diplo- 

 graptidi, are separated on account of the rectangular fixation of the thecae 

 and the location of the apertures. This family comprises the genera Retio- 

 graptus, Climacograptus, Dicranograptus, Dicellograptus and Monoclimacis. 

 It will be noticed that Freeh unites here, by the direction and shape of the 

 thecae, forms of very different appearance, as the biserial Climacograptus and 

 uniserial Monoclimacis and transfers the genus Retiograptus, hitherto united 

 with the Retioloidea, but in which the latticed sculpture of the periderm is 

 still little developed, to the Climacograptidi. The family Diplograptidi has 



