16 PERMO-CARBONIFEROUS FOSSIL CLIFFS. 



to recoo'nise the stratigrapliical position of the beds 

 further inland, where among a higher series they are to 

 be found — as also along the higher members of the sea 

 cliffs to the east occur tiie limestone bands, quarried for 

 the Portland Cement Works of the ]\Iaria Island Com- 

 pany. The works lie inland, in a valley, towards the 

 head of Bernacchi's Creek. 



The common forms, Fenestella internata, Lons., F. 

 pleheid, jNI'Coy, and Frotoretepora amjda, Low, make up 

 the greater part of the Fenestella Zone. Associated 

 with them, however, may be found the following typical 

 forms, viz :— - 



Spirit'era Tasmuniensis Morris 



„ Darwiiiii „ 



„ glaber „ 



„ duodecimcostata M'Coy 



Productus brachythserus G. Low. 



Strophalosia Clarkei ... Eth. 



„ Jukesii Eth. Jr. 



Pleurotomaria Morrisi M'Coy. 



(4.) Productus Zone, — The series of beds overlying 

 the Fenestella Zone are divided by Mr. Montgomery 

 into two groups. The first group in succession termed 

 by him The Productus Zone is about 30 feet thick, com- 

 posed largely of beds of blue hydraulic limestone from 

 6 inches to 4 feet thick These are the beds chiefly 

 worked at the quarries for the production of Portland 

 cement. The blue limestone bands are separated from 

 each other invariably by beds of calcareous shale and 

 mudstone. The limestones are replete with the common 

 forms of Spirifera, Strophalosia, Productus, Avicu- 

 lopecten, Stenopera, Crinoids, and Fenestella. Pachy- 

 domus, common, but less frequent. 



(5.) Crinoid Zone — The next and highest groups in 

 position of the Darlington beds are estimated by Mr. 

 Montgomery to be about 320 feet thick, and are termed 

 by him the Crinoid Zone. This zone is composed 

 of limestones, consisting chiefly of crinoid remains, 

 occurring in beds from six inches to four feet thick, 

 separated by thin shaly partings. Mr. Montgomery 

 states that this limestone seems very pure, except 

 that it frequently contains bands and masses of chal- 

 cedony ( Buhr stone )^ formed by the infiltration and 

 segregation of silicious solutions. The beds of the 



