TRILOBITES AND OTHER FOSSIL CRUSTACEA. 195 



Nature in all her varied moods which makes such 

 enthusiasts of geologists. Not even botanists are 

 more devoted to their hobby ; and it is undoubtedly 

 this enthusiasm which makes geological investigation 

 independent of companionship 

 for success. 



The absorption of most, if not 

 all, of the Lower Silurian rocks 

 into the Cambrian system has, 

 of course, largely increased the 

 number of localities where fossils 

 are to be obtained. The Mene- 

 vian beds near St. David's, in 

 South Wales, are exceedingly 

 rich in Trilobites ; among which 

 Paradoxides Davidis, the largest 

 of its order, is abundant. This 

 species sometimes attains a 

 length of two feet, and is, there- 

 fore, strongly contrastible in this 

 respect with the little Agnostus 

 (Fig. 1 50) and the Phillipsia (Fig. 

 156). The South Welsh Valleys are comparatively 

 little explored, although the geological student might 

 do so to his double advantage, for they are equally rich 

 in scenery and in fossils. Monmouthshire presents 

 an area of country where we have, perhaps, a more 

 varied geological outcrop than anywhere else in Great 

 Britain. Near Newport a patch of Silurian strata 



1 60. —Apus productns 

 (recent). , 



