434 Q. C. Crick — Jurassic Cephalopoda — 



Affinities and differences. — In its general form and ornamentation this 

 species closely resembles Ammonites Sauzei, d'Orbigny (Pal. FranQ. 

 Terr. Jur. vol. i. 1842, p. 407, pi. cxsxix.). A specimen of the latter 

 from the Inferior Oolite of Sherborne, Dorset (Brit. Mus. No. C. 3230), 

 61 mm. in diameter, gives the following measurements : Width of 

 umbilicus, 19 mm. ; height of outer whorl, 24 mm. ; thickness of 

 outer whorl, 30 mm. Allowing for the compression of the Australian 

 specimen, d'Orbigny's species was probably a more inflated shell 

 with somewhat coarser ornaments and fewer umbilical ribs (14-15). 



In its sculpture Ammonites Bainii,^ Sharpe, from Sunday Eiver, 

 S. Africa, somewhat resembles the present species, but it has much 

 more inflated whoi'ls, and a narrower and deeper umbilicus. 



From such forms as Ammonites biplex,^ J. Sowerby, the present 

 species is at once distinguished by the presence of a tubercle at the 

 point of bifurcation of each umbilical rib. 



In proposing for the Australian form the specific name Woodwardi, 

 the writer has great pleasure in associating with the fossil the name 

 of Mr. H. P. Woodward, Government Geologist, Western Australia. 



Locality. — Champion Bay, Western Australia. 



Ammonites (SpTiceroceras) semiornatus, sp. nov. (PI. XIII. Figs, la, 6.) 



1870. Ammonites Broechii, C. Moore, Quart. Journ. Geol. See. vol. xxvL 

 pi. XV. f. 4. 

 Sp. char. — Shell discoidal, somewhat inflated; greatest thickness at a point 

 distant from the umbilicus about one-third of the width of the lateral area, about 

 one-third of the diameter ; height of outer whorl about one-third of the diameter 

 of the shell. Whorls six; inclusion two-thirds, diminishing considerably in the 

 outer whorl, so that at the commencement of the outer whorl the inclusion is not 

 one-half ; umbilicus wide, rather deep, exposing the inner area of the whorls. 

 Suture-line imperfectly seen, and depth of chambers unknown. "Whorl lunate in 

 section at base of body-chamber, and about as wide as high, becoming at the 

 anterior part of the body- chamber more elliptical in section, and rather higher than 

 wide ; periphery convex, forming a continuous curve Avith the sides ; inner area 

 sloping towards the umbilicus, feebly convex. Each whorl ornamented with about 

 twenty-two primary ribs, slightly curved and forwardly inclined, extending from the 

 suture over about one-third of the width of the lateral area ; each then dividing into 

 three, or more rarely into two, less prominent ribs which cross the periphery without 

 interruption, the number of these peripheral ribs being about sixty-nine to a whorl. 

 Up to the point where the diameter of the umbilicus is 8 mm. the inner area of the 

 whorls (as seen within the umbilicus) is quite smooth. 

 Dimensions : — 



Diameter of shell 61 mm. 



Width of umbilicus 22-5 ,, 



Height of outer whorl 20 ,, 



Thickness of outer whorl 17'5 ,, 



The specimen from which the above measui-ements were taken has a maximum 

 diameter of 64 mm., but at this diameter the other dimensions cannot be so 

 accurately determined. The anterior portion of the body-chamber appears to be 

 slightly crushed, so that the thickness of the outer whorl as given above is probably 

 too small. 



Bemarhs. — The description given above is based upon a single 



1 Trans. Geol. Soc. [2], vol. vii. 1847, p. 197, pi. xxiii. f. 2. Pavlow (Bull. 

 Soc. Imp. Nat. Moscow, n.s. vol. v. 1892, p. 493) places this species in a division 

 (Astieria) of Neumayr's genus Olcostephanus. 



2 Min. Con. vol. iii. p. 168, pi. ccxciii. 1821. 



