70 



PROCEEDINGS OF THE GEOLOGICAL SOCIETY. 



portion of the fauna of the lowest Cambrian rocks. No less than 

 9 genera and 26 species occnr in the Menevian rocks alone of North 

 and South Wales ; or, in other words, more than half the known 

 fauna is Trilobitic. In the Menevian beds occur the first known 

 Cystidean, a few fragments having been found by Dr. Hicks, in 1872, 

 associated with Pteropoda (Theca) and Entomostraca. The finding of 

 Paradoocides Davidis and P. Hicksii at Dolgelly, on the same horizon 

 as that of St. David's, immediately above the " Cambrian" sandstones 

 (Harlech and Barmouth beds), in bands of uncleaved Menevian slate 

 and ashes, aids greatly in the correlation of the two areas. This, with 

 other evidence, justified Hicks and Salter in regarding the Menevian 

 and the Lower Lingula-fiags as a well-marked division or subgroup 

 differing from the Upper Lingula-fiags, quite as much so as do the 

 Upper Lingula-fiags from the overlying Lower Tremadoc slates (as 

 now understood) : for, with few exceptions, the species in each are 

 peculiar, and they possess many peculiar genera. I may mention 

 the following as genera that first appear in the Menevian beds ; and 

 those marked with an * are confined to that horizon : — 



^Protocystites. 

 ^Arenicolites. 

 ■kArionellus. 

 *An(ypolenus. 

 ^Erinnys. 

 ^Holocephdlina. 

 *Carausia. 



Primitia. 

 ? Orthis. 



Obolella. 

 * Gyrtoiheca. 

 •xStenotheea. 



Although four species of Protozoa (Protospongia . diffusa , Salt., 

 P. fenestrata, Salt., P. major, Hicks, and P. flabetlata, Hicks) 

 occur at St. David's, the three first named species commenced in 

 the Harlech beds below, P. flabellata being Menevian only. 



No Protozoa have yet been detected in the North-Wales area. 

 Prior also to the year 1863 we had no knowledge of the exist- 

 ence of the gigantic Oleni, revealed to us by the researches of 

 Salter, who disentombed the great Paradoocides (P. Davidis) from 

 the black slates of Porth-y-rhaw and Solva Harbour, thus showing 

 the occurrence side by side in the same beds of the largest 

 Trilobite known with Agnostus the smallest. Both these genera 

 are remarkable ; and their extremes widely depart from the general 

 type. 



A valuable paper was communicated to our Society in 1867, 

 vol. xxiii., by Prof. Harkness and Dr. Hicks, " On the Ancient Eocks 

 of St. David's Promontory, South Wales, and their Fossil Contents." 

 The authors dealt fully with both the geology and the palaeontology 

 of that remarkable promontory. The chief portion of the labour and 



Cystidea . . 

 Annelida . . 

 Crustacea . . 



5? * ' 



JJ • • 



Ji • • 



)) • • 



5J • • 



Brachiopoda 

 Pteropoda . . 



