202 Proceedings of the Boyal Physical Society. 



the localities assigned being Ashantee and Guinea. The 

 next specimen, Causus Rhombeatus, will also be found in Dr 

 Gray's list, p. 163, No. 86, with its synonyms (Hab. West 

 Africa ; Gold Coast, Liberia, South Africa) ; but it is, more 

 fully described in the catalogue of reptiles of the British 

 Museum, 1844 (Snakes, p. 33). Of this snake the British 

 Museum possesses four. The specimen named Boodon Geo- 

 metricus will be found, with its synonyms, in Dr Gray's list, 

 p. 159, No. 42, under the name Bocedon Geometricus, Hab. 

 West Africa ; and the specimen named Onycliocephalus 

 Liberianus will be found with the single synonym Onyclio- 

 cephalus Liberiensis, under the name Onychopsis Liberiensis, 

 in Dr Gray's list, p. 157, No. 18 ; Hab. Liberia, Calabar. 



The last remaining specimen to be noticed is a lizard, 

 Tiliqua Fernanda, described in the British Museum Cata- 

 logue (p. 110, Lizards) as Tiliqua Fernandi — the Fernando 

 Po Tiliqua — of which an interesting account has already 

 been given to this Society in a paper by Mr Andrew Murray, 

 at p. 415 of the first volume of its Proceedings. The oblique 

 cross brown bands along the brown sides should be bright 

 scarlet or vermilion, but stuffed or preserved specimens seem 

 to lose this brilliant colour, as it is not to be seen in the pre- 

 sent specimen, although otherwise in excellent preservation. 



V. On the Silicification of Organic Bodies. By Alexander Bryson, Esq., 



F.K.S.E. 



The solution and deposition of silica has become a very im- 

 portant question, not only to the mineralogist, but to the 

 physical geologist. Whilst the mineralogist has speculated 

 on the forms of silicious minerals and fossils, he generally 

 has arrived a priori at the conclusion that they were of aqueous 

 origin ; the geologist, on the other hand, has assumed them 

 mostly as due to igneous action. M. Brogniart was the first 

 to point out the true theory of the silicification in fossil woods, 

 in an able paper published in the " Dictionnaire d'Histoire 

 Naturelle." In 1828 Von Buch communicated a paper to the 

 Academy of Sciences of Berlin, in which he boldly asserts that 

 the silicifying process never immediately attacks the calcare- 

 ous shell ; that it develops itself only upon the organic sub- 



