Vol. 52.] LLANDOVERY AND ASSOCIATED ROCKS OP CONWAY. 285 



Conway. 



Scotland. 



Lake District. 



Central 

 Wales. 



Llandovery Beds. 



Zone of 

 Rastrites 

 maximus. 



Upper 

 Birkhill. 



Middle 

 Skelgill. 



Upper 



Skelgill. 





* Rastrites maximiis (Carr.) 



* 



* 



* 



* 



* 



* 

 * 



* 

 * 

 * 

 * 

 * 

 * 

 # 



* 

 * 

 * 



* 

 * 

 * 

 * 



* 



* 

 * 

 * 



* 

 * 



* 



# 

 * 



* 

 * 



* 

 * 



* 



* 

 * 



* 

 * 

 * 



* 

 * 

 * 

 * 



* 

 * 



* 

 * 

 * 



* 



gemmatus (Barr.) 



* distans ( Lapw. ) 





* Monograptus argutus (Lapw.) ... 

 Barrandii (Tullb.) 



* concinnus (Lapw.) 



* cyphus (Lapw.) 



crassus (Lapw.) 



* cireaarius (Lapw.) 



galaensis (Lapw.) 



Hisingeri,va,r.nudus(L&pvr.) 



involutus (Lapw.) 



* lobiferus (M'Coy) 



runcinatus (Lapw.) 



* spinigerus (Nich. ) 



* turriculatus (Barr.) 



Pet alogr aptus ovatus (Barr.). ... 

 * Diplograptus Hitghesii (Nich.) ... 

 * pahneus (Barr.) 



sinuatus (Nich.) 



* tamariscus (Nich.) 



* Climacograptus normalis (Lapw.) 



As shown by this table, the correspondence between the fauna 

 of the Conway beds and that of the Upper Birkhill Shales is very 

 close. As the study of our fossil lists will show, the species are 

 by no means evenly distributed throughout the three bands. 



Some forms, which are very rare in the zone of Rastrites maximus, 

 are far more characteristic of the Tarannon Shales ; such, for 

 instance, as' Monograptus turriculatus, M. galaensis, M. pandus, and 

 M. Barrandii. Others occur more abundantly in the lower bands 

 (2 and 4), and may indicate .the presence of lower zones. Mono- 

 graptus gregarius is fairly common in band No. 2, but we have 

 succeeded in obtaining only one specimen from the zone of Rastrites 

 maximus. 



Rastrites peregrinus was found only in the lowest band (No. 2). 

 The poverty of the fauna from this lowest band was no doubt in part 

 due to the very small extent of the exposure ; had we been enabled 

 to work it better, we probably should have found it possible to 

 definitely determine its age. 



2. The Tarannon Shales. 



The correlation of the lowest fossiliferous band of the Tarannon 

 Group is a matter of some difficulty. We did not succeed in finding 



