Cambrian Faunas. 260 



brian beds of China, but the resemblance is a distant one; 

 the Chinese species is much nearer G. tucer of Billings, from 

 the Olenellus beds in Vermont. 



The four species of Concephalites found in Sardinia, ap- 

 pear rather to form a special group, distinguished from 

 others by the possession of a frontal tubercle. A parallel 

 case among the Conocoryphinse is Ctenocephalus which is 

 distinguished from Conocoryphe proper by a tubercle simi- 

 lar to that of these Conocephalites. No Conocoryphes are 

 known in this fauna, though they are so common in the 

 Cambrian rocks of the opposite coast region of France. 



A still more remarkable deficiency in this fauna is the 

 absence of the genus Agnostus. 1 We know of no para- 

 doxidos fauna and scarcely any Cambrian fauna of trilo- 

 bites in which this genus does not make its appearance. 

 The tests of this genus are usually found in the greatest 

 abundance in fine dark shales, and especially in the Tessini, 

 Davidis and Forchammeri sub-zones of the North of Europe. 

 The Sardinian deposits are described as of a coarse texture, 

 this would account for the scarcity, but not for the en- 

 tire absence of the genus. 



A fifth species of Conocephalites is described by Prof. 

 Meneghini, (C. inops) which is of a different type from those 

 with pre-glabellar tubercle. It is a Euloma rather than a 

 Conocephalites, and it is rightly compared to C. Geinitzi of 

 the fauna of Hof in Bavaria. But this fauna by its facies is as 

 modern as the Tremadoc slate. Some imperfect examples of 

 Anomocare also are figured, a genus which in the North of 

 Europe, appears first in the Upper Paradoxides beds. 



This fauna of the lower zone in Sardinia appears to be 

 composed of forms descended from ancestral types of the 

 Parodoxidean family, mingled with precursors of the 

 numerous forms of Conocephalites ' 2 which showed them- 



1 In these remarks I have assumed that the memoir describes 

 all the trilobites found; and also that the fossils of the lower zone 

 are all of one faunal group, as I see no intimation to the contrary. 



'-' The name Conocephalites is here used for such forms as ( . 

 Bavaricus and C. Wirthi of the fauna of Hof. 



