No. 2.] THE ''colonies" of m. barrande. 197 



most strongly marked affinities with those of the Lower Silurian 

 rocks of Britain and America. This is especially shown by the 

 occurrence of the genera Diplograj^sus, Climacogi-apsus, and 

 Rastrites, none of which is known to be represented in the Upper 

 Silurian of any other country except Bohemia. Not only is this 

 the case, but a large number of the species of Etage E are iden- 

 tical with those of the Caradoc beds (Couiston mudstones) of the 

 north of Eudand, and of similar strata in the south of Scotland. 

 I shall, however, elsewhere endeavour to show that the Grapto- 

 lites of Bohemia were introduced by emigration from the British 

 area. 



i. Crinoids. — No certain remains of Crinoids have been hither- 

 to detected in the colonial zone, except in one doubtful instance. 

 It should be noticed, however, that Crinoids are very rare in the 

 second fauna, whilst there are several species of Cystideans. On 

 the other hand, crinoidal fragments are extremely abundant in 

 e 1, although the number of specific forms seems to be very small. 



j. Corals. — Corals have hitherto been found in only one colony, 

 and here there is only one indubitable species, viz., Calamopora 

 (^Favosities) alveolaris. As no corals of this group are known in 

 the second fauna, and as they are common in the earlier phases 

 of the third fauna, this establishes another link between the latter 

 and the colonial fauna. 



C. Relationships of the Colonial Fauna as a Whole. 



Regarded as a whole, the following conclusions may be drawn 

 from a study of the fossils occurring in the colonies : — 



1. Altogether 110 species of fossils are known to occur in the 

 colonies, and although this number is still incomplete, it is to be 

 remarked that the total is little smaller than that of band d 5, in 

 which the colonies are situated, and in which 130 fossil species 

 are known in all. It is a very singular fact, therefore, that these 

 110 species should be " cantoned " so to speak, amongst 130 

 species belonging to the older second fauna. 



2. The independence of the colonial fauna, in spite of its 

 general connexion with the third fauna is shown by the existence of 

 fourteen species exclusively confined to the colonies. This number 

 indicates the amount of extinction which took place in the inter- 

 val between the last colony and the definitive appearance of the 

 third fauna in Bohemia. It is to be noticed, also, that it is the 



