Distribution of the Rhabdophora. 425 



At Balleymoney near Gorey, in the adjacent county of 

 Wexford, a similar group of forms is met with, viz. : — 



Didymograptus (Hisingeri). Diplograptus mueronatus, Hall. 



Dicellograptus sextans, Hall. Climacograptus (bicomis ?), Hall. 



Leptograptus flaccidus ?, Hall. Dicranograptus rainosus, Hall. 



The most prolific locality, however, appears to be that of 

 Six-Mile Bridge, county Clare, on the western slope of the 

 Slieve Bernagh mountains. From this locality Mr. Baily 

 quotes 



Ccenograptus gracilis, Hall. Diplograptus Baylii, Carr. 



Dicellograptus sextans, Hull. f'oliaceus, Mxirch. 



Climacograptus bicornis, Hall. Didymograptus, sp. (Plisingeri). 



and some others. 



Wales. — The Graptolitic black mudstones of Llanfaelrhys, 

 Ang'lesey, noticed by Mr. Salter, probably belong also to this 

 doubtful horizon. They occur in the neighbourhood of lime- 

 stones of Bala age, and yield Dicranograptus formosus* , Hopk., 

 Climacograptus Scharenbergi, Lapw., and species of Didy- 

 mograptus. 



America. — The typical Glenkiln fauna of South Scotland 

 reappears almost unmodified in corresponding strata on the 

 continent of North America. It is confined to the con- 

 voluted shales that form the banks of the Hudson River in 

 the neighbourhood of Albany, and to their Canadian equiva- 

 lents. These so-called Hudson-River shales were formerly 

 regarded by the great majority of American palaeontologists as 

 the representatives of the Lorraine shales that form the 

 highest member of the Ordovician of Western New York. I 

 have myself advocated the theory that they are of much 

 earlier date, and inferior in systematic position to the Trenton 

 Limestone. In the face of recent discoveries, however, neither 

 of these theories appears to be any longer tenable. Mr. Whit- 

 field's opinion, that they correspond, generally speaking, to 

 the Utica Slates of Western New York and Canada, is pro- 

 bably the nearest to the truth ; but it is possible that some 

 of the fossils quoted from them belong in time to the upper 

 beds of the Trenton Limestone of the west. 



At the locality of Norman's Kiln, near Albany, Professor 

 Hall has collected 



Clematograptus multifasciatus, Ccenograptus gracilis, Hall. 



Hall. surcularis, Hall. 



Didymograptus serratulus, Hall. Dicranograptus ramosus, Hall. 

 superstes?, Lapw. furcatus, Hall. 



* Salter, Mnm. Geol. Survey, vol. iii. p. 256 ; Quart. Journ. Geol. Soc. 

 vol. viii. p. 359. 



