Ordoviclan Rucks. 



(c) Stratigraphical Horizon. 



Such being the forms present little doubt would have arisen as 

 to the stratigraphical position of the beds but for the presence of 

 Phyllor/rajAus and Goniograptus which in this district were thought 

 to have disappeared in the Middle Castlemainei beds. In New 

 Zealand, however, Phyilograptus is recorded in association with 

 typical Upper Castlemaine (zone 1) fornis2. The discontinuity of 

 its range is therefore not so great as appears at first. (See Note 2 

 infra.) A similar anomaly with Fhyllograptiin is recorded by 

 Ruedemann^, who in a table showing the range of different species 

 records P. august if alius for Beds 1, 2, 3, and 6 of the Deep Hill 

 Series, while he omits it from Beds 4 and 5. No possible arrange- 

 ment of the beds will make all genera range continuously, and it 

 must be left to later work to supply an adequate explanation. The 

 polyphylogenetic origin of Goniograpius may be held to lessen the 

 importance to be attached to its occurrence. To place the Victoria 

 Gully Beds above the Darriwil Beds — which would be necessary to 

 provide a continuous range for Phyilograptus — would break the 

 continuity of the range for several other genera — for example, 

 Loganograptus, Tri gonograptus, Oncograptus, and Glossograptns. 

 The fauna of the original or Upper Darriwil beds seems good evi- 

 dence that these forms have been correctly placed, unless we are to 

 suppose that these Darriwil beds are themselves Middle Castlemaine, 

 ■a theory which 1 do not think sufficiently Avell supported to need 

 combating. The presence of at least three genera of the Diplograp- 

 tidae indicates a high horizon. 



(d) The Evidence from Bidymogrnptus caduceus (Salter). 



The evidence to l)e derived from the study of the development 

 •of Didymograpfus caduceus seems to point to a high position for- 



1 Geol. Castlemaine, op. cit. 



2 Bell, J. M., Parapara Subdivision, N.Z. Geol. Surv. (n.s.), Bull., No. 3. 



The forms recorded are said to be from one horizon, Tetragraptus, Didymoiiraptas, 

 LoganorjraptMf, Climdcograptut and Pht/Uograptusi oocurrin<? on the same slab. 



Fitfures are given of the following species— the comments in parentheses are mine. 

 Rattyitex (obscure fragments which may or may not belong to that genus). 

 Dldi/inngrapttix fxtensuii (several figures representing two or more species of horizontal 



Diiipmograptng ). 

 Tetragraptus quadrllirachiatus (T. Serra). 

 Loganograp'iig nctobrachiatus Cnon L. Logaiii vel D. oclohracfnatus. An identical form 



is found in Upper Castlemaine beds here). 

 Phi/Uugraptus typus. 

 Diplograptus sp. 



Didymograptus caduceus (typically Upper Castlemainian (zone 1) form). 

 Climacograptus (doubtful identification i. 



3 Grap. N.Y., I., p. 506. (Bed 4 is omitted from the table throughout). 



