cal Society. 435 



Subfamily Madoquittjb. 



1 I by. 

 A.n example of M. ki \ British East A.frica {F. C. 



Selous) agrees wifcli th i sn of M. phillipsii descri 



li\' me in L910 in the structure of the pedal glanda and the 

 absence of inguinal glands. There v. p lira of mammas. 



The Madoquinae (Marfoqua and Dorcotragus) differ from 

 the other antelopes c tnsidered in this paper by t!ie structure 

 of the muzzle and rhinarium. 



PROCEEDINGS OF LEARNED SOCIETIES. 

 GEOLOGICAL SOCIETY. 



April 17th, 1918.— Mr. G. \V. Lamplugh, F.i: 



lent, in the Chair. 



The following communication was read : — 



•The Evolution of the Liparoceratidae.' By Arthur Elijah 

 Trueraan, M.Sc, F.G.S. 



The Ammonites considered include several sub-parallel series, of 

 which four genera were indicated by Mr. S. S. Buckman in 

 ' Ybrkshir Ammonites. 1 The details of ontogeny and the 



sutures, which had not hitherto been compared, have been em- 

 ployed in constructing tables showing both the biological and 

 the stratigraphical relations of the various species; a revision 

 of the existing classification is proposed. 



The early members of each re similar ' Capricorn ' forms 



with slender whorls and stout ribs (for instance, A. Capricorn us, 

 A. lateecosta, A. maculatus). In somewhat later examples the 

 outer whorl is swollen, and has paired tubercles (for instance, 

 A. heterogenes). From this stage the tendency is to shorten the 

 period with slender Capricorn whorls by accelerating the develop- 

 ment of bituberculation and prolonging the period of pre-costate 

 globose whorls ; thus the most advanced members of each series 

 are stout bituberculate forms (for instance. A. striatus, A. bechei), 

 which do not pass in development through a Capricorn stage. 



The following genera may be recognized ; each includes am- 

 monites of the three types mentioned above : — 



1. An earlier group, with tubercles paired in the involute 

 stages ; Radstock (Somerset) is the only British locality where 

 these ammonites have been found. 



odiceras, gen. nov. Elevated whorl, paired tubercles, the inner and 

 outer rows widely separated. Genoholotype, Ammonites striatus 

 parinodxis Quenstedt (1884, pi. xxviii. fig. 6). 

 Gen. nov. Round whorl, with the rows of tubercles placed close 

 together. Genoholotype. a specimen to be figured as a new 

 species. 



