436 G. C. Crick — Jurassic Cephalopoda — 



Compared with Ammonites Gervillii, J. Sowerby,' [^Ammonites 

 Brongniartii (pa7-s), A. d'Orbigny,^] the Australian fossil is less 

 inflated and diifei'ently ornamented, whilst the greater inclusion of 

 its whorls, its narrower umbilicus, and the smoothness of its inner 

 whorls distinguish it from Ammonites polymerus, W. Waagen ^ 

 \_Ammonites Brongniartii (pars) d'Orbigny].* 



The British Museum Collection contains examples of an apparently 

 undescribed species from the Inferior Oolite of Dundry, Somerset, 

 which resemble the present species most closely ; they have, how- 

 ever, a somewhat larger umbilicus, finer ornaments, and their inner 

 whorls (as seen within, the umbilicus) are distinctly ribbed, even 

 where the umbilicus has a diameter of only 2-5 mm. 



Locality. — Champion Bay, Western Australia. 



Ammonites (Perisphinotes, W. Waagen). 



Ammonites (^Ferisphinctes) Championensis, sp. no v. (PI. XIII. 



Figs. 2 a, b, and c.) 



Sp. char. — Shell (cast) discoidal, with somewhat inflated whorls ; greatest thick- 

 ness near the margin of the umbilicus, exact thickness unknown ; outer whorl about 

 two-fifths of the diameter of the shell in height. Number of whorls not seen; 

 inclusion (in the outer whorl) about three-fifths ; umbilicus not very deep, wide, 

 about one-third of the diameter of the shell in width. Whorl somewhat oval or 

 almost lunate in section, probably wider than high ; indented to about two-fifths 

 of its height by the preceding whorl ; periphery probably narrowly convex ; sides 

 convex ; inner area steep, almost perpendicular, slightly convex. Chambers shallow. 

 Suture-line rather complex, incompletely known ; outer saddle only partly known ; 

 the first lateral lobe deep, narrow, trifid ; the first lateral saddle much broader than 

 the first lateral lobe, divided into four principal branches, that forming the most 

 anterior portion of the suture-line being again divided by a secondary lobe into two 

 branches, the outer of which is again subdivided by a small lobe ; the second lateral 

 lobe scarcely one-half the size of the first lateral lobe, indistinctly trifid, the median 

 portion being very short ; the second lateral saddle small, divided by a small lobe 

 into two unequal branches, the inner of which is again subdivided by a minute lobe ; 

 between the second lateral saddle and the suture of the shell three auxiliary lobes and 

 saddles. Each whorl ornamented with about nineteen or twenty compressed, not 

 very elevated, short ribs, or radially elongated tubercles, each giving rise to three or 

 four rounded, slightly elevated ribs, thirty-eight of which can be counted in half a 

 Avhorl, the interspaces being of about the same width as the ribs. 



Dimensions : — 



Diameter of the shell about 115 mm. 



Width of umbilicus , 39 ,, 



Height of outer whorl about 45 ,, 



Thickness of outer whorl (?) ,, 



The thickness of the outer whorl cannot be ascertained, since only one side of the 

 specimen is preserved. 



Remarlcs. — The above diagnosis has been drawn up chiefly from 

 a natural cast about 115 mm. in diameter, consisting of one side of 

 the outer whorl fairly well preserved, bearing fragments of the test 

 and exhibiting the greater part of the suture-line ; the inner whorls 

 are not preserved. The collection, however, includes another speci- 



' Min. Con. vol. ii. p. 189, pi. clxxxiv. a, fig. 3. 

 - Pal. Fran9. Terr. Jm-. i. p. 403, pi. 137, ff. 3, 4 {non ff. 1, 2, 5). 

 ^ Ueber die Zone des Ammonites Sowerbyi, Benecke's Geogn.-palaont. Beitrage, 

 vol. i. p. 605. 

 4 Pal. Fran9. Terr. Jur. i. p. 403, pi. 137, ff. 1, 2 (jion ff. 3, 4). 



