2 Field Naturalists' Club — Proceedings. [vd."xxxiii. 



gizehensis, var. lyelli, d'Archiac, represents the microspheric 

 shell of a dimorphic couple ; whilst the small form, N. 

 curvispira, Meneghini, represents the megalospheric stage. 

 In other words, the two forms belong to one true species 

 having an alternation of generation. There are also casts of 

 molluscs, probably referable to Mevetrix and Panopcsa. A 

 piece of Olivine Dolerite was also shown, which forms part 

 of a pavement of a ruined temple on the east side of the 

 Pyramid of Cheops. The Biotite Granite with unusually 

 bright flesh-coloured felspar came from the Valley Temple of 

 Kephren. 



PAPER READ. 



By Mr. J. Shephard, entitled " A Visit to the Great Lake, 

 Tasmania." 



Before showing an interesting series of lantern slides depicting 

 some of the principal natural features of the country around 

 Hobart and along the route to the Great Lake, the author, 

 by means of a geological sketch map, pointed out the struc- 

 tural configuration of Tasmania, and mentioned that geological 

 research pointed to the probability of the massive columnar 

 diabase that formed the extensive plateau occupying the 

 central portion of the island, and constituting the capping of 

 Mounts Wellington, Ben Lomond, and Barrow, having been 

 injected, during post-Jurassic times, between the Permo- 

 carboniferous strata and the then overlying Mesozoic beds. 

 Subsequently, the forces of denudation, acting throughout 

 protracted periods of geological time, removed the super- 

 incumbent beds, exposed the igneous sill, and, attacking it in 

 turn, interrupted its continuity, as the isolated residuals on the 

 mounts mentioned would seem to demonstrate. Several views 

 of tesselated sandstone pavements were shown, and the opinion 

 expressed that this unique natural phenomenon could only have 

 been induced by heat derived from the proximity of an igneous 

 rock. The south-western portion of the island, it was mentioned, 

 was practically unsettled, and very little had been accomplished 

 in the interpretation of its geological features. The vegetation 

 of that portion consisted chiefly of the so-called " Horizontal 

 Scrub." The exploration of an area whereon this distinctive 

 growth predominated had to be made at an elevation of many 

 feet above the ground, by stepping from branch to branch. 

 Many prospectors, it was alleged, had penetrated into this 

 wilderness, but few had returned to detail the privations they 

 had endured. The formation of " blow-holes " in favourably- 

 jointed rocks exposed to the force of the sea was dealt with, 

 and a series of views shown depicting their ultimate transition 

 to an abrupt-sided rift or gorge. Finally, the chief features 

 of the Great Lake were detailed, and some account given of 



