174 



PKOCEEDINGS OF THE GEOLO&ICAl SOCIETX. 



Trilobites, lately published, we find the following results given, with 

 reference to those forms discovered in the lowest or Paradoxides 

 zones in different parts of the world. The groups are those given 

 by him in the Tables. 





Bohemia. 



Spain. 



Scandinavia. 



England. 



America. 





27 

 



■■'5' 



■"2" 

 1 

 5 



9 



2 



6 



'" "i" 



77 

 ■■5" 



2 



■"s" 



4 



33 



1 

 4 

 4 



7 



""e" 



"" i* ' 



2 



2G 



""e" 

 ■■■■{■ 



Other Crustaceans. . . 

 Ostracoda 



Annelids 



Pteropods 



Grasteropods 



Braohiopods 



Bryozoa 





Sponges 







40 



19 



96 



58 



33 



Prom this Table it will be observed that England has |)roduced eight 

 of these groups, whilst none of the other countries has yielded 

 more than five. It is, however, most interesting to note the similarity 

 of types in regions so far apart, and the close resemblance of the 

 faunas. Though animal life was restricted to these few types, yet 

 at this early period the representatives of the several orders do not 

 shoAV a very diminutive form, or a markedly imperfect state, nor is 

 there an unusual number of blind species. The earliest known 

 brachiopods are, apparently, as perfect as those which succeed 

 them; and the trilobites arc of the largest and best-developed types. 

 The fact also that trilobites had attained their maximum size at this 

 period, and that forms were present representative of almost every 

 stage in development, from the little Agnostus with two rings to the 

 thorax, axi^ Microdiscus with four, to Erinnys y^iih. twenty-four, and 

 blind genera along with those having the largest eyes, leads to the 

 conclusion that, for these several stages to have taken place, nume- 

 rous previous faunas must have had an existence, and, moreover, 

 that even at this time, in the history of our globe, an enormous 

 period had already elapsed since life first dawned upon it. The 

 following are the species noAV to be described. 



Agnostus davidis, Salter. PL Y. figs. 2-4. 

 Brit. Assoc. Report, 1865. 



This is the largest species found in the Menevian group, being about 

 ■| inch long. Head rounded and forming about two thirds of a circle, 

 and about | inch wide. Surrounded by a narrow border. The 

 glabella occupies about one third of the width, and tapers forwards. 

 It is divided at the base of the anterior third by a transverse 

 furrow, into an anterior spheroidal lobe and a posterior elongated 

 lobe, the anterior part of which is raised centrally; there is a 

 triangular lobe on either side at the base of the glabella. Cheeks 

 slightly raised, and gibbous. 



Thorax depressed, strongly trilobed ; pleuree grooved deeply to 



