New Species of Leperditia. 5 



base of this laminated and calcareous mudstone series, (?) crus- 

 tacean tracks were noticed ; also a Lingula and some bivalve 

 remains. 



Above the Leperditia Bed. — 10 feet of calcareous mudstone 

 with no fossils. Then 3 feet of comparatively fossiliferous lime- 

 stone with Heliolites sp. and Spirifer plicatellus. Above this 

 again, 18 inches of unfossiliferous micaceous sandstone. Then 

 3 feet of calcareous mudstone, highly fossiliferous, containing 

 of. Cystiphyllum sp., Rliizoj^hylhtm inter punctatwtn, De Kon. ; 

 R. robustuin, Shearsby ; Try plasma sp. ; Favosites sp. ; Helio- 

 lites cf. inter stincta, L. sp. ; Orthothetes shearshii, Dun ; Spirifer 

 aff. plicatellus, L. sp. ; Murchisonia sp. ; and Encrinurus cf. 

 punctatus, Briinn. sp. Laid down upon this are 150 feet of 

 shales and mudstones capped by a few feet of impure limestone 

 containing an enormous number of fossils, some of which are : — 

 Cyathophyllum sp. ; Heliolites sp. ; Crinoid remains ; Lingula 

 aff. lewisi. Sow.; Orthothetes shearshii; Atrypa reticularis, 

 L. sp. : cf. Meristina australis, Dun ; Spirifer aff. *S'. fimbriatus, 

 Conrad ; (cf.) Paracyclas sp. ; (cf.) Megamhonia sp. ; Bellerophon 

 sp. ; (?) Endoceras sp. Over this there are about 150 ft. of 

 grits, sandstones and calcareous shale, which is finally cut off by 

 porphyry. 



EXPLANATION OF PLATES. 



Plate I. 



Fig. 1. — Leperditia shearshii, sp. nov. A right valve of a small 

 individual, la, dorsal edge view. x 10. 



Fig. 2. — Z. shearshii, sp. nov. Type. Carapace from the right 

 side of a normal-sized individual. 2a, ventral edge 

 view. X 10. 



Fig. 3.— Z. shearshii, sp. nov. Cast of a large individual, show- 

 ing the deep marginal depression. x 10. 



Fig. 4. — Z. shearshii, sp. nov. Portion of interior of a valve, 

 showing " eye-spot " with vascular markings. x 20, 



Plate IL 



Photograph of section of the Upper Silurian strata at Clifton wood, 

 Yass. (The white line marks the Leperditia bed). 



