Reports & Proceedings — Zoological Society of London. 285 



(h) With wide ES, reaching to the outer tubercles. 



^goceras, Waagen. EL and IL about equal in depth, IL symmetrical. 



Genolectotype, Ammonites planicosta, d'Orbigny. 

 Androgynoceras, Hyatt. IL and EL about equal in depth, IL asymmetrical. 



Genolectotype, Ammonites hybf-ida, d'Orbigny. 

 Oistoceras, S. S. Buckman. Eibs with sharp peripheral curve. Suture 



similar to Androgynoceras. Genoholotype, Ammonites figulinus, 



Simpson. 

 Amblycoceras, Hyatt. Eibs with slight peripheral curve. IL shallower 



than EL. Genoholotype, A. capricormis, Hyatt, 1900. 



These ammonites generally occur in the upper part of the Lower 

 Lias, where it has been usual to recognize a capricornus zone over- 

 lying a striatus zone. Careful collecting has shown, however, that 

 there are several horizons with capricoru ammonites of different 

 series and several with the involute forms evolved from them, as 

 shown below : — 



• , , fBituberculate ammonites of the A. nautiliformis series. 



mm garitatus zone -y ^^ ^^ Oistoceras. 



^Capricorn ,, Oistoceras. 



Bituberculate ,, the A. bechei series. 



,, ,, ^gocerasa,nd Androgynoceras. 



,, ,, Amblycoceras. 



Capricorn ,, Amblycoceras. 



^ ,, ,, JEgoceras, Androgynoceras. 



C ,, ,, Beaniceras. 



■ ih«^ ^ -.o I Bituberculate ,, Liparoceras. 



Capricorn ,, Liparoceras. 



^Bituberculate , , the first group (with paired 



tubercles). 



In no locality that has been examined is the complete sequence 

 shown. The absence of some groups is due to the original distri- 

 bution of the ammonites; in other cases it is due to non-sequences 

 (for example, the upper part of the davmi zone is not represented in 

 Crloucestershire). 



Two groups of Lias Ammonites are recognized, namely: (i) those 

 •which were evolved directly fi-om a globose ancestor ; this includes 

 the Liparoceratidse, Echiocei'atidse, Hildoceratidse, Polymorphidse, 

 Deroceratidae ; and (ii) those which passed through an intermediate 

 broad- veutered (cadicone) stage; these include the Araaltheidae and 

 Dactyloidse (with Beaniceras). 



davcei zone 



III. — Zoological Society of London. 



Jpril 9, 1918.— Dr. A. Smith Woodward, P.R.S., Vice-President, 

 in the Chair. 



Dr. A. Smith Woodward, F.RS., V.P.Z.S., exhibited fossil rostral 

 teeth of the sawfishes J^opristis and Prutis, and referred to the 

 progressive changes in the rostral teeth of the Pristidse during 

 geological time. 



Mr. G. A. Boulenger, F.Pt.S., exhibited the head of an example of 

 Hydrocyon goliath, Blgr., from the Congo, a fi.sh attaining the length 

 of 4 feet. The object of the exhibition was to show the enormous 



