196 OUR COMMON BRITISH FOSSILS, 



abounds in several species of Trilobites, notably 

 AsapJms and Ogygia (Figs. 139 and 155). Builth has 

 been noted for the number and beauty of its Ogygia 

 Biichii. 



Maentrog and Port Madoc have long been cele- 

 brated for their rich yields of Trilobites. The student 

 may obtain them, in many places, from the slates 

 wkich build up the walls by the roadside, whilst in 

 the quarries there are usually bands or seams espe- 

 cially full of them. Few localities are better worth 

 a visit, for we are here within the charming circle of 

 Snowdonia. The lower Lingula flags are well deve- 

 loped at Maentrog, and one Trilobite is so abundant 

 in them that it was proposed to call them " Olenus " 

 beds. Two species of the obscure little Agnostiis are 

 associated with it, along with various other fossils. 

 At no great distance up the higher parts of the valley 

 is Festiniog. A diminutive railway, with cars of the 

 same proportion as the narrow diameter of its " per- 

 manent way," runs up one side of the valley to Fes- 

 tiniog, and the geological student can take advantage 

 of it in his rambles, and thus pass over the outcrop 

 of beds rich in Trilobites. A locality for Cambrian 

 Trilobites is the neighbourhood of Dolgelly, a district 

 whose magnificent scenery of wild mountain and 

 umbrageous valley is annually drawing to it a larger 

 number of tourists and visitors. Here Conocoryphe^ 

 Agnostics, etc., may be found in certain places in 

 tolerable abundance. The student might advan- 



