1867.] TATE LOWEE LIAS OF lEELAND. 303 



ill this country as good forms of the " Bucklandi- or Lima-beds ;" 

 but I cannot now regard them as a proof that the beds containing 

 them belong to that series. I so placed this zone in my former 

 paper ; this error arose from an imperfect knowledge of the fauna of 

 the Ammonites-angidatus zone ; but the thorough acquaintance 

 which I now have of it enables me to rectify the mistake. 



The fauna viewed as a whole is Hettangian ; that is, it is identical 

 with that of the Gres infraliasique de Hettange, with that of the 

 zone of Ammonites Moreanus of the Cote d'Oi% and that of beds 

 which in other districts are known by local names, but all of which 

 represent one stage in the vertical series of the Liassic deposits, and 

 are inferior to the beds with Ammonites BucTclandi and Lima gigantea. 



5. The Zone 0/ Ammonites Bucklandi. — At Waterloo, Larne, com- 

 pact blue limestoues with thin shaly bands, and containing Qryphcea 

 incur va, overlie the shelly limestones of the " Angulatus-zone ;" and 

 the stratigraphical superiority of a series of beds charged with 

 Gryphcea at Glynn, two miles south of Larne, to the Angulatus- 

 beds is incontestable. Again, beneath the " Hibernian Greensand," 

 in the Tircreven Burn, Downhill, Londonderry, limestones and shales 

 similar to those at Waterloo, and containing Grypliaia, are to be seen 

 resting on the calcareous grits peculiar to the north-west of the Liassic 

 area, which I have referred to the zone of Ammonites angidatus. 



These beds, characterized by GryplicEcc incurva, constitute a higher 

 horizon than the shelly limestones of the " Angulatus-zone," and are 

 separable from them by lithological and palteontological features. 



The Gryplicea cuxuata (G. incurva) is the ever- accompanying 

 fossil to those characteristic of this zone ; it occurs in great profusion, 

 and is in striking apposition to the Ostrea irregularis, one of the domi- 

 nant forms of the " Angulatus-beds " below. Gryphcea arcuata is 

 unquestionably here aud there a fossil of the zone of Ammonites an- 

 gulatus, but is of rare occurrence. In England I record it as very 

 rare in the "Angulatus-zone^' at j^Iarton, Lincolnshire; Terquem 

 quotes it as ti^es rare from the same horizon. 



If Mr. John Jones's notion, that Ostrea irregularis and Grypha^a 

 incurva are but different states of the same species, be true, then it 

 favours, keeping in view the restricted range of these two forms, 

 the supposition that the zones of Ammonites angulutus and A. BucTc- 

 landi are contemporaneous in the same region. The marked varia- 

 tions of form of the aggregate species conveniently designated 

 Ostrea, gryphus, Linnseus, thus would arise from difference in habitat, 

 the subspecies 0. irregidaris beiug the shore form, and 0. arcuata 

 {Gryplicm incurva') representing that of the deeper water. This 

 may be correct ; for the large Gasteropod fauna of the zone of Am- 

 monites angulatus demonstrates that the beds of that series were 

 deposited in comparatively shallow water, whilst those of the 

 Ammonites-BucMandi zone, with few Gasteropods and numerous 

 Cephalopods, were accumulated in deeper seas. The more frequently 

 occurring species are : — Ammonites Bucldandi, A. semicostatus, Ostrea 

 {GryplKxa) arcuata, Lucina ovalis, Cardinia Listeri, Pleurotomaria 

 similis, Pentacrinus hasaltiformis, and Mo7itlivaltia Haimei ? 



