196 THE CANADIAN NATURALIST, [Vol. 



VI. 



/. Br a chiojyo da. ^Only fifteen species of Br ichiopods are known 

 in the colonial fauna, and these occur in three colonies only. The 

 brachiopods are, therefore, poorly represented ; but the following 

 conclusions may be drawn from such as are present : Firstly, five 

 genera and eight species suddenly occur in the Colony Zippe, in d 4, 

 which band hardly contains anything else but Orthides. Secondly, 

 the colonies contain the genus Spirifer, which is not known at 

 all in the vsecond fauna of Bohemia, and is equally very rare in 

 the Lower Silurian of other countries. The genus, however, is 

 abundantly represented in the first phases of the third fauna. 

 Thirdly, we meet in the colonies with Atrypa reticularis, which 

 is equally unknown in the second fauna of Bohemia, and is com- 

 paratively rare in the Lower Silurian series elsewhere. On the 

 other hand, it is a characteristic species of the Uj^per Silurian 

 series from its base almost to its summit. Fourthlv, of the total 

 number of fifteen species, only one is exclusively colonial, and that 

 doubtfully so. Fourteen species, therefore, establish the connex- 

 ion with the third fauna. 



g. Lamellihranchiata. — The most remarkable forms of this 

 class in the colonies belons: to the o^enus Cardiola, the most im- 

 portaut species being C. fibrosa^ Sow, C. interrupta. Sow, C. 

 gihhosa, Barr., and U. nigrans, Barr. Not one of these species 

 is found in any formation belonging to the second fauna, but all 

 reappear at different horizons in the third fauna. 



h. Grap)tolites. — These are very abundant in the colonies, and 

 show many points of affinity with those of the third fauna, 

 whilst '' they have only few affinities with those of the contempo- 

 rary phases of the second fauna.'' Twenty-one species of Glrap- 

 tolites occur altogether in the colonies, and they give rise to the 

 following conclusions : — Firstly, not one species of the colonial 

 fauna c:in be positively asserted to occur in the second fauna (Lower 

 Silurian). Secondly, fourteen species of the twenty-one reappear 

 in band e 1, and of these six pass on into e 2. There remains 

 seven forms which are peculiar to the colonial zone, and these are 

 found exclusively in the Colony Archiac. 



The Grraptolites, therefore, contribute largely to establish the 

 connexion between the faunae of the colonies and of the Upper 

 Silurian rocks of Bohemia, no single form being certainly known 

 to be identical in the colonies and the contemporary phases of the 

 second fauna. It is to be noted, however, that the Graptolitas of 

 the colonies, as well as those of e 1 and e 2, show upon the whole 



