286 



DR. A. E. THrEMAN OX THE 



[vol. lxxiv, 



Oistoceras curvicorjstjm (Schlcenbach ). 



Ammonites curvicornis Schlcenbach, ' Ueber den Eisenstein des Mittleren 

 Lias in JSTord-West Deutschland, &c.' Zeitschr. Deutsch. Geol. Gesellsch. 

 vol. xv (1863) p. 522 & pi. xii. 



This differs from A. curvicornum Wright (8, pi. xxxi, figs. 3 

 & 4) in having a rounded venter, that of the latter being 

 flattened. Wright's form has also more prominent tubercles. 

 The probable relations of these species are shown in Table III. 



Table III, showing the probable relationships of the species 

 of the Liparoceratidce. 



Zones and Sub-Zones 













Anisoloboceras 



margaritatus * 





Oistoceras 

 alloeotypum 



O.curvicornum.Wt. O.curvicornum.Sch 



\ V 



O.fiqulinum O.tfTfiqulinum 



O.omissum 



i 



nautiliformis 

 1 



Oistoceras •< 



<— 



| 



Becheiceras 



bechei 



1 





daedalocosta 4 





Androgy 

 divar 



noceras | Ae 9 0< 

 tcosta daeda 



1 A?he 



eras 



ocosta Amblycoceras 

 Tlcyi dissotypuro 



1 

 1 

 1 



1 



1 









A.hy 



jrida 



. 1 

 A.crescens 











>- 





1 



1 A.?Sinuosum 



1 / 



| A.brevilobatum 















1 









lataecosta ■« 





A.obtus 



1 



icosta / A. lata 



/ 



ecosta / 











— 



A.macu 



■ 

 latum .' A.aequ 



/ 



■' 



icosta 













1 



Liparoceras 

 cheltiense 



L.heptangulare 







ibex i 





J 



.'l.pseudostriatum . , J , 

 r ■-.. Lobtusinodum 



L.heterogenes 

 l.sparsicosta 



L.zieteni 









v„ 



ParinoLera ■ 









'A.adnethicus 



ann °l ICer3S 



minodiceras 

 | 















• 







< 



1 ■ 

























1 



1 













[Continuous vertical lines^proved range of the genus ; broken line s= probable 

 range ; dotted lines indicate affinity ; for daedalocosta read daedal icosta.] 



O. curvicornum (Schlcenbach non Wright) may be represented at 

 Waddington, near Lincoln. The form figured by Wright occurs 

 at a corresponding level (the Oistoceras sub-zone) in Dorset. 

 • In each of these series three types may be distinguished : 



(1) With peripheral costse sharp and distinct. 



