IN THE ANGLO-PARIS BASIN 135 



considered it to be of Aptian age. Douville (1906) recognised it to be of Albian age 

 and figured a fragment (1906 ; pi. II, figs. 1, ia) which Spath (1930b ; 65 footnote) 

 'later renamed Prolyelliceras peruvianum, the type species of his ' genus '. Riedel 

 (1934 ; pi. 9, figs. 9-1 1) figured another specimen as Prolyelliceras? lobatum confirm- 

 ing a Middle Albian age for these forms, because they are associated with Lyelliceras 

 of the lyelli type also figured by him. From specimens in the British Museum (Nat. 

 Hist.) e.g. BMNH C 74786 J. V. Harrison Colin., from the road between Viola and 

 Portillo, it is apparent that these so-called ' Prolyelliceras ' are in fact large specimens 

 of Lyelliceras of lyelli-ulrichi type, the ornament of which modifies at diameters which 

 are as yet unknown in the old world. Prolyelliceras is considered here to be a junior 

 subjective synonym of Lyelliceras, and the lyelli Subzone is apparently well repre- 

 sented in Colombia. 



(b) Peru 



In the last twenty years our knowledge of the Middle Albian zonal stratigraphy of 

 Peru has been greatly increased by the work of Knetchel (in Knetchel el al., 1947) 

 and Benavides Caceras (1956). It is apparent that the lyelli Subzone is well repre- 

 sented in the Pariatambo, Crisnejas and Chulec formations classified by Benavides 

 Caceras with the Zone of Oxytropidoceras carbonarium. These sediments, between 

 100 and 200 metres thick, have yielded ammonites such as Desmoceras latidorsatum, 

 Lyelliceras lyelli, L. ulrichi and Eubrancoceras aegoceratoides , all known from localities 

 in the Anglo-Paris basin, especially at Courcelles (Aube). It is interesting to see that 

 Benavides-Caceras records Lyelliceras pseudolyelli from Bed 20 of the Crisnejas 

 locality classified by him with the underlying Knemiceras raimondii Zone. It is also 

 instructive to compare the sequence of Zones recognised in Peru with that of Algeria. 

 As yet Mojsisovicsia has not been found in the lyelli Subzone in the Anglo-Paris 

 Basin but it does occur in the overlying spathi Subzone where it is represented by 

 M. delaruei and subspecies. The genus is represented in Peru by the type species of 

 Mojsisovicsia, M. ventallinensis (Gabb) whose exact Subzonal age is uncertain 

 (Douglas 1921). It is also uncertain at present whether there are any higher Middle 

 Albian sediments than those of the lyelli Subzone preserved in Peru, but it appears 

 that the Subzonal sequence is incomplete reflecting the break in sedimentation seen 

 elsewhere in the World. 



(vii) TEXAS 



Young (1966) has presented an extremely important work on the ammonite 

 zonation of the Fredericksburg Division of the Texas Albian and on the mojsisovic- 

 siinid ammonites contained in it. He presents a correlation of the Texas zonal 

 sequence with that of Europe. Following a discussion of the faunal sequence both 

 in Texas and elsewhere outside the United States, he examines four possible con- 

 clusions raised because of an apparent anomaly which exists between the carbon- 

 arium Zone of Peru and that of Texas. In Peru the carbonarium Zone of Benavides 

 Caceras contains Lyelliceras and it is here correlated with the lyelli Subzone of the 



