126 llevieivs — Barrandes Silurian Sijdcm, Bulieinia. 



to the basic dykes of Bijawar age as their possible nidus.'''' So far as 

 we know at present, the almost invariable association of the diamond 

 in South Africa with ultra-bLisic rocks inclines us to believe that its 

 birthplace occui's in a magma of this character. Hence the basic 

 dykes so often quoted by Mr. Vredenburg may really be the original 

 home of the gem, though the basic material itself could never endure 

 the attrition inevitable in the formation of a conglomerate. 



To use a popular expression, these Panna diamonds are "small 

 potatoes and few in a hill," whilst their derivative character helps us 

 very little towards a recognition of the source whence they originally 

 proceeded. The majority of the crystals are said to be small, yet 

 of a good water and lustre, and very seldom clouded or flawed. Their 

 commonest defect consists in the pi'esence of ' spots,' which are black, 

 opaque inclusions of jagged outline. Owing to this defect a large 

 number of the stones are unfit for the European market. 



(^To he concluded in our next mtmber.) 



TV. — SYSTiiME SiLUEiEN Du Centre de LA Boh£;me, par Joachim 

 Bareande. 1^ partie : Becherches Paleontologiques. Continua- 

 tion editee par le Musee Boheme. Vol. iv : Gasteropodes, par le 

 Doct. Jaeoslav Perner. Tome i, 1903; Tome ii, 1907. Traduit 

 par A. 8. OuDiN. 



rpHIS work supplies a need that has been long felt by palgeontologists 

 _L studying the Gasteropoda of the Paloeozoic rocks. As is well 

 known, Barrande succeeded not only in accumulating an immense 

 amount of material connected with the ancient fauna of Bohemia, but 

 he also wrote a considerable number of volumes thereon. He, 

 however, died before accomplishing the part on the Gasteropoda, 

 and in his will desired Professor W. Waagen to continue it. Illness 

 and subsequent death prevented this. Therefore, in April, 1900, the 

 Barrande Commission requested Dr. Perner to undertake the work, 

 and all the materials collected by the eminent Prench refugee were 

 placed in his hands. 



After a careful study of these large quartos, with due consideration 

 for the difiiculties involved, we must congratulate the Commission on 

 the result of their choice. Dr. Perner shows not only extensive 

 knowledge of the Gasteropoda of his own country but also of other 

 countries, and he brings to bear on the subject a great breadth of 

 observation, as well as a faculty for minuteness of detail. The 

 translation into fluent French renders the work easy of comprehension 

 hj foreigners. 



In the prefaces to the two parts Perner describes the diflSculties he 

 has had to contend with, the mode he has thought best to meet them, 

 as well as the scope of the work. The material consisted of specimens, 

 notes, and sketches accumulated between 1847 and 1883 — the year of 

 Barrande's death — and also of some 247 lithographed plates. These 

 plates contain a superabundance of figures, not merely of different 

 families and genera of Gasteroj)oda (often mixed up unsystematicallj'), 

 but they even include various organisms belonging to other branches 



