708 EEPORT— 1888. 



Concerning Reptilian Life. — By far the best terrain 13 that of red sandstone ; 

 then follows mesozoic limestone, granite, tertiary, and lastly palfeozoic terrain. 

 Granite is more than two times better than palaeozoic, nearly equal to Jurassic and 

 cretaceous, and slightly better than tertiary terrain. Palaeozoic terrain is many 

 times less favourable than that of red sandstone and nearly three times worse than 

 Jurassic and cretaceous grounds. 



The effect of the nature of the various sorts of terrain upon the whole flora and 

 the healthiness of the country is remarkable. 



An interesting fact is also this, that most of the snakes which frequent the 

 sterile Jurassic and palreozoic rocks are lizard-eaters, whilst the two species of 

 Tropidonotus are nearly absent. 



It was found that altitude, annual mean temperature, or the annual amount 

 of rainfall by far less influence the distribution of Reptiles and Amphibia in the 

 peninsula than the nature of the soil. High and long granitic ranges of mountains 

 may in many cases afford no obstacle to the spreading of certain creatures, whilst 

 other terrain, like limestone — although perhaps forming low and narrow tracts 

 only — may act as a most effective barrier. 



In conclusion, the wish is expressed that similar data, referring to other countries, 

 may be forthcoming to enable us to verify and to correct the conclusions made in 

 this paper. For the present Ihey cannot be anything but suggestions, which, how- 

 ever, may, with more material to work with, prove capable of wider application. 



5. On the Natural History of Christmas Island, 

 Bij J. J. Lister, M.A., F.Z.8. 



Her Majesty's siu-veyiug vessel ' Egeria ' reached Christmas Island on Friday, 

 September 30, 1887. 



In the distance the sides of the island were seen to rise moderately steeply, and 

 a shallow saddle in the middle ended in two low, rounded elevations, one of which 

 was the summit, near the western end. On nearer approach the whole island was 

 seen to be uniformly covered with bush, except where the bare face of a line of 

 inland cliffs appeared. The general physical features of the island are treated of in 

 Captain Aldrich's report.* The greatest length is 12 statute miles. It rises from 

 deep sea. Soundings of over 1,000 fathoms were obtained at five points round the 

 island, all within four miles of shore. Its volcanic origin is proved by the presence 

 of lumps of ' compact olivine basalt and basalt tuff' at the foot of a cliff, and of a 

 bed of ' altered volcanic stones ' near the summit.^ No volcanic rock was, however, 

 found in situ. The surface formation of the parts of the island explored is lime- 

 stone. This rock forms the summit, 1,195 feet above the sea, and covers the sides, 

 broadening out at successive elevations into terraces which rise one above another 

 on the sides of the island. The rock is traversed by vertical fissures which isolate 

 tall pinnacles often 12 or 20 feet in height. The surface is weathered into 

 irregular hollows and sharp projecting points. Fi'om the base of the lowest inland 

 clifi' a gradual slope leads to the sea, terminating in a shore cliff from 15 to 60 

 feet in height. This has a vertical face and is much uuderworn by the waves. 

 In some places, where the sides slope less steeply into deep water, beds of live 

 coral are seen. 



The geological history of the island appears to be shortly as follows. The 

 summit of a submarine volcanic mass has been slowly elevated above the sea to a 

 height of nearly 1,200 feet, and, as it has passed through the zone of lime-forming 

 organisms in shallow water, these have invested it with a cap of limestone. The 

 upheaval has been arrested at intervals and allowed the formation of reefs which 

 have since been elevated and form the terraces on the sides. At the projecting 

 headlands, where the chief stress of the ocean currents fell, the reefs have grown 

 less than in the intervals between them, and since their elevation the action of the 



' Report on Christmas Island (Indian Ocean), H.M.S. 'Egeria.' 1887. Captain 

 P. Aldrich, R.N. « Loc. cit. p. 15. 



