SONNINIA— SUMMARY. 453 



namely, pi. iii, fig. 3, " Hammatoceras (Sonninia) poly acanthum, Waag., Sauzei- 

 kalke;" and pi. v, fig. 6, "Hammatoceras (Sonninia) Andium, Gottsche, Sauzei- 

 kalke." The identification of the first can scarcely be accepted, for it differs in 

 many respects widely from Waagen's species. It is one of the " renovate " series 

 (p. 448), but it is not comparable with any of the forms figured in this work at 

 present. The identification of the second is, unfortunately, still less to be trusted. 

 It is a costate form which would apparently fall into the column III, b (p. 449) ; 

 but the central whorls are wanting. In its mode of costation it agrees most 

 nearly with Sonn. multicostata ; but it is a very much thinner shell with quite 

 different proportions. 



In Gottsche's work, 1 though there are some species of Sonnininge, there seem to 

 me to be no species of Sonninia — nothing, at any rate, like the Goncavum-zone 

 forms. The only other extra-European species of Sonninia which I can call to 

 mind at present is Ammonites pustidifer, figured by Bayle and Coquand. 2 At one 

 time the identification of this species with one of the Goncavum-zone forms seemed 

 likely (see p. 258, foot-note 2) ; but a strict examination negatived the idea. Two 

 striking characters may be mentioned, and either one of them will be sufficient 

 to indicate that further comparison with the Goncavum-zone species is unnecessary. 

 First, though nodiferous, the Chili fossil is angustumbilicate ; second, the nodi 

 are sessile. Accordingly, though the Chili fossil is only a fragment, there need 

 be no uncertainty ; the student can easily see that none of the Goncavum-zone 

 species figured have sessile nodi — the nodi, or tubercles of different kinds, are all 

 pedigerous (see p. 405, note to Sonn. spinicostata). 



Thus none of these South American species of Sonninia give any clue to the 

 origin of the Goncavum-zone forms ; in fact, they all show characters indicative of 

 further biological advance. All of them are more nearly related to species which 

 do occur in this country at a higher horizon ; but, independently of this, a study 

 of the characters of the South American species in comparison with those of the 

 Goncavum-zone Sonniniae would lead to the supposition that the former were of later 

 date than the latter ; that is to say, if specimens like the South American forms 

 were submitted without any indication of horizon or locality, the answer to the 

 question of date would be " between the times of Concavum and Humphriesianum." 



It is not a little remarkable, then, to find that in the case of the South 

 American fossils described by Moricke their horizon is said to be " Sauzei-kebYke," 

 not only because of the occurrence of certain fossils, but because the strata in 



genossen herausgegeben von Dr. Gustav Steinmann," ' Neues Jahrbuch f. Mineral., &c.,' Beilageband 

 ix, Stuttgart, 1894. 



1 ' Beitrage zur G-eologie und Palaeontologie der Argentiniscben Republik. II. Palaeont. Tbeil. 

 III. Abtheilung. Ueber jurassiscbe Versteinerungen aus der Argentiniscben Cordillere, Cassel,' 1878. 



2 "Foss. Sec. Chili," 'Mem. Soc. Geol. France,' 2e serie, vol. iv, pt. 1, pi. ii, figs. 1, 2, 1851. 



