No. 2.] THE •• COLONIES ■' OF M. BARRANDE. 193 



nate beds of quartzite. Id all cases, witli the exception of the 

 colony Zippe, the colonies are intercalated in this portion of fZ 5 ; 

 and there are also numerous beds (" coulees '') of trap at various 

 horizons. As will be seen immediately, this portion of d 5 is 

 chiefly distinguished from the beds of the colonies by the fact that 

 the schists are almost wholly destitute of graptolites. 



D. The Colonies. — The colonies, as just remarked, are situated 

 in the schistose lower portion of d 5, and they are lithologically 

 absolutely undistinguishable from band e 1, consisting of grapto- 

 litic schists with calcareous concretions and interbedded traps. 

 The following distinctions, however, may be noted as compared 

 with el: — 



1. The thickness of the colonies is always much less than that 

 of band e 1 ; and there are fewer alternations of the graptolitic 

 schists with the traps. 



2. Certain colonies are composed entirely of schists without 

 traps. 



3. In some colonies (e. g. Colony Haidinger and Colony Cotta) 

 there are bands of gray schists and quartzites like those of d 5. 



4. The calcareous concretions are generally rarer in the colonies 

 than in the band e 1, and they even appear to be wanting in some 

 colonies, especially in the deepest {e. g. m the Colony Haidinger.) 



E. Bund fZ, 4: — This band is composed of impure schists, 

 which are always highly micaceous and deeply coloured, brown, 

 gray or black. Though fissile, they are niuch less homogeneous 

 and papery ('' feuilletes ") than those which constitute the supe- 

 rior band d 5. Sometimes there are intercalated beds of quartz- 

 ite, and occasionally there are interbedded sheets of trap. There 

 is only one colony in d 4, namely the Colony Zippe, situated with- 

 in the ramparts of Prague. This colony differs from all the rest 

 by its being entirely composed of a lenticular mass of limestone, 

 about 25 centimetres thick, intercalated in the midst of regular 

 alternations of schist and quartzite. 



IV. Pal^ontological Relations of the Colonies. 



From what has preceded, it is evident that stratigraphically 

 the colonies belong to the Lower Silurian series, and we have now 

 to enquire what relationships can be shown to subsist between the 

 colonial fauna and the second and third fauna respectively. The 

 specific connexions of the colonial fauna, when examined in de- 

 VoL. VI. K No. 2. 



