302 PROCEEDINaS OP THE GEOLOGICAL SOCIETY. [May 22, 



The proportion of the number of species peculiar to the zone to 

 those appearing in higher horizons is great compared with that 

 observed in other districts : thus Terquem and Piette enumerate 67 

 species belonging to this zone, only 9 of which are special to it, 

 whilst 58 pass to superior horizons, and, moreover, 2 of the 9, 

 though confined to the " Planorbis-zone " in the east of Prance, 

 are fossils of higher stages in other parts of Europe. Thus the 

 zone of Ammonites planorhis is really wanting in palseontological 

 characters ; even the Ammonite which gives its name to the set of 

 beds is not peculiar to it, and the horizon is recognized, independently 

 of its position and lithology, by the absence of certain forms rather 

 than by an assemblage of species. 



4. The Zone of Ammonites angulatus. — That portion of the Lower 

 Lias of Ireland which is undoubtedly the representative of the 

 Infra-lias (true) of the Continent, comprises, as before stated, the 

 greater mass of that formation. The zone attains its greatest de- 

 velopment, in thickness and in organic remains, on the east coast 

 of Antrim (where it is exposed), on the eastern shore of Larne Lough, 

 at "Waterloo, Larne, at Glenarm, and at a few other localities. It 

 consists at these places of a series of thinly bedded shelly lime- 

 stones alternating with marls or clays, and at Waterloo is not less 

 than 35 feet in thickness. This zone is represented in Colin Glen 

 near Belfast by 1 foot of calcareous marl, the fossils of which, 

 though not numerous, are those . which characterize the highly 

 fossiliferous beds of the before-mentioned localities. 



■ In the north-west extremity of the Liassic area, as at Craig and 

 Gortmore, and in the Tircreven Burn, the rock is a calcareous grit. 

 General Portlock, who obtained many fossils from this grit, stated* 

 that they were wanting in the other localities. This is no longer 

 true, as I have found all the species in the shelly limestones of 

 Island Magee, Glenarm, (fee. 



The fossils of the Ammonites-angulatus zone have been exten- 

 sively collected, especially at Island Magee, where the beds occupy, 

 at the base of the Cretaceous escarpment, a narrow strip of low ground 

 extending for about a quarter of a mile along the east shore of Larne 

 Lough, opposite to the hamlet of Magheramorne. The number of 

 species obtained amounts to 98 ; the most characteristic of these, the 

 majority of which may be collected by hundreds, are : — 



Ammonites Jolinstoni, Sow. {A. intermedius, Portlock) ; Cerithiiim 

 gratiim, Terq. ; C. JSemele, D'Orb. ; Turritella inornata, Terq. ; Pha- 

 sianella Morencyana, Piette ; Turbo suhelegans, D'Orb. ; Actceonina 

 fragilis, Dunker, sp., Ostrea irregularis ; Terquemia arietis, Quenst., 

 sp. ; Lima gigantea, Sow. ; L. jpunctata, Sow. ; L. Terquemi, Tate ; 

 L. acuticosta, Mlinst. ; L. Hettangiensis, Tqm. ; Leda tenuistriata, 

 Piette ; Astarte consohrina, Chap. & Dew. ; Cardinia ovalis, Stutch- 

 bury ; Unicardium (vel Lucina) cardioides, Phill., sp. ; Cidaris Ed- 

 luardsi, Wr. ; Pentacrinus Briareus, Mill. ; Montlivaltia Haimei, 

 Cha]p. & Dew. ; and SerjJula socialis, Goldf.f 



Several of the species given in the above list of fossils are known 



^ Loc. cit. p. 139. t For a complete Hst of species see pp. 311-313. 



