94 Ernest W. Skeats .- 



submitted the collection to Mr. Hall for mure detailed examina- 

 tion, and he has kindly identitied the foUowings forms : — 



Didymograptus caduceus, Salter. 



Tetragraptus serra (sensu stricto) Broiign. 



Diplograptus, sp. 



Trigonograptus, sp. 



Lasiograptus, sp. 



Glossograp'tus, sp. 

 Also specimens of Rhinopterocaris uuiccoyi, Eth. tils., and sponge 

 spicules. 



Mr. Hall adds the following notes: — "The horizon is that of 

 the Upper Castlemaine series, although the presence of Glosso- 

 gi'aptus is suggestive of the horizon of the Darriwill series. The 

 species of Diplograptus is similar to one which occurs as low 

 down as the Victorian Gully beds at Castlemaine, but is in- 

 distinct. Trigonograptus is known from higher beds, but pos- 

 sibly occurs at Castlemaine. The presence of graptolies in the 

 Eocene (?) conglomerate on the beach near Frankston has be^n 

 recorded by Mr. Pritchard and myself.^ We announced the pre- 

 sence of Diplograptus, but ventured no further. At the same 

 time I found a specimen which I thought might be Didymo- 

 graptus caduceus, but it was so indistinct that I thought it wiser 

 not to mention it, especially as the record of even the genus 

 would have upset the generally-received opinion as to the age of 

 the slates of the district." The discovery of these graptolites 

 provides the evidence previously wanting for determining the 

 age of the Moorooduc rocks, clearly shows their Lower Ordovician 

 character, and Mr. Hall's determinations show that the rocks 

 belong to the Upper Castlemaine, or possibly the Da.rriwill 

 series, a higher horizon than that of the graptolitj bearing rocks 

 previously described irom the southern part of the Peninsula. It 

 is now probable that all the slates and sandstones of the Morn- 

 ington Peninsula belong to the Ordovician series. The grapto- 

 lites were found on a steeply sloping part of the hillside, where 

 no observations of the dip or strike of the beds could be 

 obtained. At a lower level the Ordovician rocks pass below the 

 Tertiary series, the general direction of the eastern boundary of 



1 I'roc. Roy. Soc. \ict., xiv., I'.iol, [i. 41. 



