120 Proceedinr/s of the Royal Irish Academy, 



In the Little River group the various zones are directly correlatable 

 with the zones of the Birkhill shales of Moffat, and with those of the 

 Skelgill beds of the Stockdale shales of Lakeland. 



The Crocknagaegan eeds, characterized by the presence of Cephalo- 

 fraptus acuminatus and Climacograptus 7tormalts, are almost certainly 

 equivalent to the C. acuminatus zone of both areas ; in the succeeding 

 Slate Quaert beds, Biplograptus modestus is, as usual, the predomi- 

 nant form, accompanied by the more striking, though less uniformly 

 distributed, Biplograptus vesiculosus and CI. medius. 



In the Edenvale beds above, IMonograpti make their first appear- 

 ance, represented by M. tenuis and M. ci/phus. These are accompanied 

 by CI. rectangidaris^ and a band at the base contains many Dimorpho- 

 grapti. These Slate Quarry and Edenvale beds taken together 

 probably represent the whole of the zone of D. vesiculosus in the Moffat 

 area; but it seems likely that the Bimorphograptus confertus zone of 

 the Lake District corresponds more accurately with the Edenvale beds 

 alone. In the overlying Mullaghnabuoyah beds, the predominant 

 JVIonograptus is M. triangulatus, though M. gregarius is present, and, 

 with CI. Tornquisti^ seems to indicate that these beds represent the zone 

 21. gregarius of Moffat, and the greater part of the beds included in 

 the zones M. Jimhriatus to M. convolutus of the Lake District. The 

 LiMEHiLL beds, characterized by the distinctive Monograptus Sedg- 

 ivickii, accompanied by M. discretus and CI. scalaris, are the equivalents 

 of the M. Sedgioickii zone in both areas, while the Petalograptus 

 band at the base may possibly represent the Cephalograptus cometa 

 zone. 



An interesting point to notice is the succession of species belonging 

 to the Climacograpti. 



In the Crocknagargan beds, CI. scalaris var. normalis is very 

 abundant ; and though this form does range up into the overlying beds, 

 it is nowhere found in such numbers as in the lowest beds. To this 

 succeeds CI. medius, characteristic of the Slate Quarry beds, giving 

 way in time to CI. rectangularis, the predominant Climacograptus 

 of the Edenvale beds. In the Mullaghnabuoyah beds above the 

 characteristic form is CI. Tornquisti ; and in the Limehill beds 

 CI. scalaris appears. 



It will thus be seen that the division of the beds based upon purely 

 lithological grounds is confirmed by the palgeontological evidence, and 

 that each lithological division has a distinct and characteristic assemblage 

 of Uraptolite forms. 



This is well brought out in Table II., on pp. 124, 125. 



