BUN 



[63] 



C A C 



BTJMA'STTJS. (from ftov^aa-To-s, ex /3oi> 

 et /ia<rTos, Gr.) The name given 

 by Sir K. Murchison to a genus of 

 trilobites, who describes one species 

 only, which he has named B. 

 Barriensis, the specific name being 

 derived from the locality where it 

 was found, near Barr, in Stafford- 

 shire. The generic characters of 

 Bumastus are thus given by Sir R. 

 Murchinson in his splendid work 

 The Silurian System: "Pars ante- 

 rior capitis rotundato-convexa, sub- 

 SBqualis : oculis lunatis, glabris, 

 remotis. Pars costalis s. corpus 

 sulcis longitudinalibus vix appar- 

 entibus, costis decem. Pars pos- 

 terior maxima, rotundato-tumida, 

 aequalis." This remarkable crus- 

 tacean, says the same author, has 

 been hitherto known in England as 

 the Barr trilobite, having been 

 found near the village and beacon 

 of Barr, in Staffordshire. A very 

 large specimen of it, five inches 

 long by 3j inches wide, has been 

 lithographed. 



BUNT. In conchology, an increasing 

 cavity ; a tunnel. 



BTTNTEE SANDSTEIN. The name given 

 by the Germans to an extensive 

 arenaceous formation of red and 

 variegated stones, composing one 

 of the sub-divisions of the Red 

 Sandstone group. In Germany, 

 this formation is distinctly separated 

 from the Keuper by the Muschel- 



kalk or shelly limestone. The 

 Bunter Sandstein of the Germans 

 is the same as the Gres bigarre 

 of the French, and the New Red 

 Sandstone of English geologists. 

 See New Red Sandstone. 



BTJBEH-STONE. This word is some- 

 times written luJir-stone. Mill- 

 stone. The substance of burrh- 

 stone, or mill-stone, when unmixed, 

 is pure sllex; it has generally a 

 reddish or yellowish colour, but 

 that of the best quality is nearly 

 white; it is full of pores and 

 cavities, which give it a corroded 

 and cellular appearance. Burrh- 

 stone is a vesicular and corroded 

 variety of common quartz. It has 

 been hitherto found only in France. 



BTSSACAN'THUS. A genus of fossil 

 ichthyolites of the Old Red Sand- 

 stone, described by Agassiz in his 

 Poissons Fossiles. 



BYSSOA'ECA. A genus of bivalve con- 

 chifera, assigned by Swainson, 

 belonging to the family Arcacea. 



BY'SSFS. (from /Jvo-o-os, Gr.) A 

 beard, as in the mytilus and pinna. 

 The lyssus is peculiar to bivalves. 



BT'SSOLITE. (from fivffcro?, flax, and 

 \i0os, a stone.) So named by 



- Saussure. A rare mineral, occur- 

 ring massive, in short, delicate, 

 and stiffish filaments, of an olive- 

 green, or brownish colour, with a 

 silky lustre, a variety of asbestiform 

 actinolite. 



C 



C'ACHOLONQ. (called also mother of 

 pearl opal : the quartz-agathe 

 cacholong of Haiiy ; the silex 

 cacholongof Brongniart.) A milk- 

 white variety of quartz, having a 

 pearly or glistening lustre, a flat 

 conchoidal fracture, and perfect 



opacity. It is found on the river 

 Cach, in Bucharia, where it occurs 

 in. loose masses, and obtains its 

 name from that river, and cholong, 

 the Calmuc word for stone. It is 

 said by Brongniart that fas cacholong 

 has been found in calcareous breccia 



