4 Frederick Ghaiwian : 



L. marginata, Keys., which may be regarded as the nearest 

 related form to ours, has been recorded from Upper Silurian 

 strata of the Swedish and Russian Baltic area. The form 

 recorded by Prof. Jones from Silurian Limestones, Pine Island 

 Lake, on the English or Great River, Canada, under the above 

 name\ was later re-determined as Isochilina grandis. A British 

 example of L. marginata is known from the Downtonian Sand- 

 stone of Kington, Herefordshire^. 



Occurrence. — In flaggy micaceous sandstone of Upper Silurian 

 age. Cliftonwood, Yass, N. S.Wales. 



Notes on the Lepbrditia Bed and Associated Strata. 



The following note on the bed has been kindly supplied by 

 Mr. Shearsby. — '' Leperditiae. These are found in large numbers 

 in a thin layer of micaceous mudstones shown in the photograph 

 (PI. TI.) by a thin white line. Myriads of these occur in a layer 

 which is not more than an inch thick. Only a few are to be 

 found just above or below this zone ; perhaps the matrix — 

 sandstone — was unsuitable for their preservation. In this thin 

 layer, also, are to be found enormous numbers of a bivalve shell, 

 probably referable to RhomhopteriaJ' 



Mr. Shearsby has kindly forwarded an interesting collection 

 of fossils associated with the Leperditiae, and has supplemented 

 these with notes of other genera and species as given below. ^ 



The Leperditia Bed. — The bivalve shell referred to by Mr. 

 Shearsby is closely allied to Rhomhopteria, and may prove to be 

 identical with De Koninck's Pterici lat/iinosa, which that author 

 recorded'* from '" argillaceous limestone, Yass District." In the 

 same bed there is a Loxonema (casts), and some crashed shells 

 of a Spirifer allied to S. plicatellus, L. sp. 



Below the Leperditia Bed. — Spirifer cf. plicatellus (narrow 

 var.) ; Favosites sp., a branching form (Mr. Shearsby has traced 

 one example for over a foot in length, giving off many branches). 

 This latter occurs 12 inches below the Spirifer bed. Near the 



1 Ann. Maj,'. Nat. Hist., ser. 2, vol. xvii., 1856, p. 94, pi. vii., %. 14. 



2 Loc. supra cit., p. 95, pi. vii., fij^. 15. 



3 Details of the separate horizons and their fossil faunas will t)e shortly };iven in a paper 

 hy Mr. Shearsby. 



4 Mem. Geol. Surv. N. S. Wales, Palseont., No. 6, 1898, p. 92, pi. iii., ti«-. 12. 



