part 4] EVOLUTION OF THE LIPAltOCEKATIDJE. 263 



Although the genera And rog y noceras, JEgoceras, Amblycoceras, 

 .and Oistoceras have typically ribs almost straight, slightly curved, 

 and markedly curved on the periphery, Amblycoceras must not be 

 •considered as intermediate between Oistoceras and Androgyno- 

 ceras or JEgoceras, for the sutures of Oistoceras are frequently 

 Aery similar to the sutures of Androgynoceras (compare, for 

 example, the first lateral lobes in fig. 8 c, p. 278 & fig. 12 a, p. 285), 

 while the sutures of Amblycoceras often resemble those of JEgo- 

 ceras, except that the first lateral lobe is shallower in Amblycoceras. 

 It may, therefore, be suggested that Oistoceras and Amblycoceras 

 arose from primitive members of the Androgynoceras and ^Ego- 

 ceras stocks respectively : probably before the latter had acquired 

 peripheral costse, but after the sutural characters of the two 

 last-named genera had become distinct. 



Becheiceras, gen. nov. 



Genoholotype : A. bechei Wright (8, pi. xli, figs. 1 & 2). 



In this series sphaerocones only are known l ; these are finely ornamented, 



bituberculate (unpaired). In development of the sphaerocones the 



Capricorn stage is omitted. Longitudinal striations are well developed. 

 Suture : EL not so deep as IL, which is often wider than ES, thus the 



greater part of IL is frequently ventral to the outer tubercles (fig. 1 b, 



p. 258). 

 Horizon. — Daedalicosta and Oistoceras sub- zones. 



The suture is most like that of Liparoceras, differing mainly 

 in the deeper first lateral lobe : JBecheiceras is, therefore, very 

 similar to the finely-ornamented involute Liparoceras, but its 

 horizon is much higher. 



Anisoloboceras, gen. nov. 



Genoholotype : A. nautiliformis J. Buckman (1, vol. i, No. 37). 

 Includes Capricorn forms and very stout bituberculate sphaerocones with 



fine ornament. 

 Suture : EL much shallower than IL, the ventral lobules of the IL 



almost uniting under the EL (fig. 1 g, p. 258). 

 Species included : — 



? A. adnethicus Hauer, ? A. ferstli Hauer, A. spinellii Hauer, A. nauti- 

 liformis J. Buckman. 

 Horizon. — The sphaerocones, which alone occur in Britain, are found in 



the margaritatus zone ; the horizon of the Capricorn forms which are 



provisionally referred to this genus is probably near the ibex zone. 



A. nautiliformis was placed with JEgoceras by Mr. Buckman, 

 Avho had not compared the sutures of these ammonites. The 

 difference in sutural proportions has alreadv been pointed out 

 <p. 259). 



The capricorns from the Adneth Shales described by F. von 

 Hauer, 2 are provisionally referred to this genus, but their precise 



1 Mgoceras capricor nu var. nodosa Futterer, ' Die Ammoniten des Mittleren 

 Lias von (Estringen ' Mitt. Bad. Geol. Landesanst. vol. ii (1893) pi. xi, figs. 1 

 & 2, may be near the capricorns of this series. 



2 ' Beitrage zur Kenntniss der Capricornier der (Esterreichischen Alpen ' 

 Sitzungsb. K. Akad. Wissensch. Wien, vol. xiii (1854) p. 101. 



Q. J. a. S. No. 296. y 



