242 



PALAEOZOIC TIME — UPPER SILURIAN. 



rensis, near fig. 177 (page 151). (b.) Ostracoids, or bivalve Crustaceans. — 

 Fig. 412, Beyrichia symmetrica, showing one of the valves; a, same, natural 

 size. 



i 



Crustaceans.— Fig. 408, Dalmania limulurus (X JD-'j 409, Lichas Boltoni (X %); 410, Ho- 

 malonotus delphinocephalus (X X /Q \ 411, Illsenus Barriensis (X }/Q 5 412, Beyrichia sym 7 

 metrica ; 412, a, same, natural size. 



The following are some of the species common to the Niagara and Clinton 

 groups : — 



Halysites catenulata (fig. 385). 

 Caryocrinus ornatus (fig. 390). 

 Hypanthocrinus decorus. 

 Lingula lamellata. 

 Orthis elegantula (fig. 329). 

 Strophomena rugosa (fig. 392). 

 Pentamerus oblongus (fig. 371). 

 Rhynchonella neglecta. 

 Atrypa reticularis (fig. 374), 



Spirifer radiatus. 



Avicula emaeerata (fig. 405). 



Orthonota curta ? 



Modiolopsis subalatus? 



Ceraurus insignis. 



Homalonotus delphinocephalus (fig. 410). 



Calymene Blumenbaehii. 



Dalmania limulurus (fig. 408). 



Illasnus Barriensis (fig. 411). 



According to Salter, a number of species of the Upper Silurian, and probably 

 of this part of it, have been observed in the Arctic ; as, Halysites catenulata, 

 Orthis elegantula, Favosites Gothlandica, Leperditia Baltica, species of Calo- 

 phyllum, Heliolites, Cystiphyllum, Cyatkophyllum, Syringopora, with Pentamerus 

 Conchidium, Atrypa reticularis, etc. ; and at the southern extremity of Hud- 

 son's Bay, Pentam,erus oblongus, Atrypa reticularis, etc. About Lake Winnipeg, 

 also, Upper Silurian fossils have been found. See Am. Jour. Sei. [2], xxi. 313, 

 xxvi. 119. 



The fossils of the Coralline limestone (p. 238), as Hall states, are mostly 

 peculiar to it. Out of 32 species (including Corals, Brachiopods, Conchifers, 

 Gasteropoda, Cephalopods, and Crustaceans) only the following are set down as 

 identical with Niagara fossils : — Favosites Niagarensis, Stromatopora concentrica, 



