76 



The eleven species that survived the period of the deposition of Division 

 1, include Stenopora fibrosa, Haly sites catenulatus, and Calymene Bliim- 

 enhachi all three of which have a great geological range, and are, in most 

 countries where thej have been found, Lower, Middle and Upper Silurian. 

 There are six new species, — Hdiolites affinis, Favosites proUficus, 

 Zaphrentis hellistriati Beatricea nodidosa, Illoenus grandis and /. orh- 

 eaudatiis. The two remaining species are Stropliomena alternata and 

 Murchisonia gracilis, and these are the only ones out of the eleven that 

 1 consider to be eminently Lower Silurian forms. In view of these facts, 

 it appears to be quite clear that during the period of the deposition of 

 Division 1 the Lower Silurian fauna became extinct in the seas of the 

 Anticosti region. 



It is remarkable that out of the 85 new species, originally described from 

 specimens collected in Anticosti, only three Beatricea undidata, OrtJiocras 

 formosum and 0. XipJdas have since been detected elsewhere. The first 

 of these occurs in the Hudson River formation at Lake St. John on the 

 Saguenay, and also on some of the Islands in Lake Huron. The other 

 two have been found in the Trenton limestone. 



2. Middle Silurian — Anticosti Group. 



Division 1. — The rocks of Division 1 rest directly and conformably 

 upon those of the Lower Silurian, above noticed, with no apparent physical 

 gap between them, although there is a palneontological break. It has been 

 already stated that 41 of the species of the lower fauna pass this break. 

 They are here joined by 45 additional species, making the whole fauna of 

 this Division to consist of 86 species, so far as is yet known. Of these, 18 

 pass upwards into Division 2 ; 13 into Division 3, and 11 into Division 4. 



Of the 41 species which are received from the Lower Silurian the 

 following are known to occur in Canada West, and New York, and are 

 variously distributed throughout all the formations from the base of the 

 Quebec group to the top of the Hudson River formation. 



Stenopora fibrosa, Halysites catenulatus, Beatricea undulata, Lingula 

 quadrata, Strophomena alternata, S. planumbona, Leptsena sericea, Orthis 

 porcata, 0. Lynx, Orthisina Verneulli, Ambonychia radiata, Subulites 

 elongata, Murchisonia gracilis, M. ventricosa, Bellerophon bilobatus, 

 Pterotheca transversa, Orthoceras formosum, Ascoceras Newberryi, Asa- 

 phus megistos, Calymene Blumenbachi and Cheirurus pleurexanthemus ; — 

 21 species. 



Among the 45 species which here made their first appearance in the 

 rocks of Anticosti we find Strophomeria rhomboidalis, S. pecten and 

 Atrypa marginalis, all three very characteristic of the Middle and Upper 

 Silurian. The new species include Atrypa umbonata and A. Primtana, 

 members of the group of which A. tumida may be regarded as the central 



