134 MIDDLE ALBIAN STRATIGRAPHY 



(iii) ALGERIA 



Although it is in need of revision, the work of Dubourdieu (1953 : 1956 ; 185-228) 

 indicates that at least the equivalent of the lower part of the lyelli Subzone is well 

 represented by sediments in the Monts du Mellegue, Djebel Ouenza, Djebel Def, the 

 environs of the Djebel Hameima, and the Djebel Bou Khadra. The ammonites 

 include Lyelliceras flandrini Dubourdieu and L. radenaci (Pervinquiere). L.flandrini 

 has extra-intercalated siphonal crenules indicating the lower part of the lyelli Subzone, 

 and this is confirmed by L. flandrini crenulata (1953 ; pi. Ill, figs. 25-35) which is 

 closely comparable to the inner whorls of the grade reached by L. gevreyi (Jacob) in 

 Bed 1 at Courcelles (Aube). L. radenaci occurs also in the lyelli Subzone of the 

 Guilford Colliery, Kent (p. 76). 



(iv) SOMALIA 



Tavani (1949) has described and figured what appears to be a lyelliceratid under 

 the name Somalites vertebralis. This is associated with Brancoceras and they may 

 well indicate the equivalent of the lyelli Subzone. However, Somalites has not been 

 found outside its type locality. 



(v) MADAGASCAR 



Collignon has demonstrated recently that the lyelli Subzone is represented without 

 question in the Middle Albian sediments of the Malagasy Republic (1963, 1965a) and 

 he employs the term Zone a Lyelliceras lyelli. Lyelliceras lyelli and close relatives 

 were found by him at Khomihevitra (1963 ; pi. 315, figs. 1333-5). It should also 

 be noted that the fauna of brancoceratids described by him (1949) from d'Ambara- 

 maninga could well indicate a basal Middle Albian age for the sediments which con- 

 tain them. The species of Pseudosonneratia from the same bed certainly do not 

 belong to that genus. Dipoloceras cristatum, and contemporary species of this genus, 

 marking the unconformable base of the Upper Albian sediments, occur at Andrano- 

 fotsy (e.g. Collignon 1963 ; 2). At present it is not possible to correlate the inter- 

 vening Middle Albian sediments, referred to a Zone a Oxytropidoceras acutocarinatum 

 and Manuaniceras jacobi in the Malagasy Republic, with those of Europe or America. 



(vi) SOUTH AMERICA 



Ammonites of Middle Albian age have been well illustrated from Colombia and in 

 particular Peru, and for the purpose of the present comparison these only will be 

 considered. Important Middle Albian faunas are also known from other South 

 American countries such as Venezuela and Brazil but these have not yet been figured 

 in full. 



(a) Colombia 



In Colombia, Gerhardt (1897 ; 168-170, pi. IV, figs. 8a, b) described an ammonite 

 which he named Acanthoceras prorsocurvatum from Ubaque (Cundinamarca) and 



