76 Scientijic Intelligence, Sfc, 



XI. — Calcaire grossler on the Garonne. 



This formation corresponding with the lower beds of the Paris 

 bason and the London clay, begins to appear over the chalk below 

 Blaye between Talmont and Mortagne, and extends along the Dor- 

 dogne to Libourne, and along the Garonne to Marmande. 1. The 

 lowest beds consist of a sandy limestone containing small quartz. In 

 it are observed Orhitolltes 'plana a fragment of echini and milliolites. 

 2. Above the former reposes a hard limestone resembling oolite, 

 containing milliolites and besides Cerithium lapidum and mutahile, 

 Amptdlaria acuta, Kchinolaynpas stellifera, &c. Then follow 

 five other beds which are all rich in fossils, especially Scutella 

 nummularia, centiculariSy polygona; Marginalis ; Fihidaria scu~ 

 tata, affinis; Echinus elegans, gacheti; JEchinolanipas ajffinis, 

 ovalis ; Spata,ngus acuminatus, grignonensis, ^'c. 



M. Desmoulins, as we are informed by Dufrenoy (Ann. des 

 Mines, vi. 430.) is engaged with the conchology of the department 

 of Gironde, which, when finished will be very important. The 

 calcaire grossier is found almost exclusively on the right bank of the 

 Garonne ; however, between Langon and Castres, it occurs on the left 

 bank. The rock at St. Macaire and Virelade, is very rich in fossils. 

 Dufrenoy enumerates above 50 shells. 



Near Reole the calcaire grossier is covered by fresh water lime- 

 stone. The calcaire grossier is represented near Bordeaux, by sands 

 which resemble the sand of the plastic clay. The same limestone 

 is observed at Landes, on the Adour, at St. Justin and Dax, where 

 numerous fossils shells have been collected. Dufrenoy gives the names 

 of45, as Ostrea sinuata, Modeola cordatay Cyprina islandica^ Conns 

 depertituSf Natica patula, Cassis pUcatula, Strombus giganteus. 



XII. — Note to Dr. JBoase's Paper, inserted at page 20. 



I regret that the additional observations, sent by Dr. Boase, ar- 

 rived too late for insertion in the present number. He has been so 

 good as favour me with a few grains of the substance which he 

 suspects to be new. I have subjected it to a hasty examination, 

 and have obtained the following results. 



It possesses a resinous appearance — is not attracted by the magnet. 

 When heated over the spirit lamp it decrepitates violently, becomes 

 almost black, and leaves a pale yellow powder which is not altered 

 per se or on charcoal before the blow-pipe. With carbonate of 

 soda it fuses into a pale green opaque bead, which becomes buff or 

 pale yel]ow on cooling. It dissolves readily in muriatic acid, leaving 

 a quantity of gelatinous silica. Caustic ammonia added to the solu- 

 tion produces a yellow flocky precipitate, which is not re-dissolved 

 by a great excess of the alkali. This precipitate being thrown on a 

 filter, and the liquid which passed through evaporated, a yellow 

 flocky precipitate appeared, resembling exactly that originally thrown 

 down by the caustic ammonia, and strongly resembling a mixture of 

 alumina and iron — not soluble in a strong solution of carbonate of 

 ammonia. — Edit. 



