14 TYPE AMMONITES— VII April 



1928 



intercalate, most conspicuous as secondaries, because the primaries 

 tend to fade away. On the line of junction there is a slight longitudinal 

 furrow. The periphery is angulate, carrying a small, raised carina ; 

 but on body chamber, periphery flattens and is barely carinate. Suture- 

 line is simple. Both specimens show at end of whorl a slight radial 

 furrow— such as often, in casts, precedes a finish to the mouth — such 

 furrow may not appear in the test, being often due to increase of thickness 

 of test to strengthen the lip of the mouth. From the run of the growth- 

 lines it would be reasonable to expect lateral projecting lappets. 



Phaularpites may be reckoned as possibly a phaulomorph of 

 Harpoceratoides, possibly as a catamorph. By its character of sub- 

 inflation of body-chamber it differs from any other Upper-Lias forms 

 hitherto observed ; but such character might, perhaps, be expected in 

 Elegantuliceras. However, Phaularpites has some resemblance to 

 Tardarpoceras, (T.A., vii, 1927, PI. DCCXLI, p. 9) ; but the suture-line 

 is less florid ; excentrumbilication is pronounced ; subinflation of 

 body-chamber is noticeable ; Pseudoliocerate ribs are not apparent in 

 umbilicus, and other ribs do not become so definitely falciform ; the 

 carina shows no trace of being hollow, and it is distinct on the cast, 

 whereas in Tardarpoceras the carina is not distinct on the cast, but there 

 is a well-marked infilling which stands up as a false keel, so that 

 ■carination of test would be strongly developed. In Tardarpoceras 

 (PI. DCCXLI, fig. 3, also to be noticed in fig. 1) the arrow marks the end 

 of the partition-band in the carina : it is situated about 7 mm., that is 

 about the length of one septum, beyond the last ( x ) : the part of carina 

 previous to the arrow is infilling ; afterwards there is a definite, strong 

 •carina in which a partition-band would be developed as a carinal septum 

 if and as the specimen grew older ; but in body-chamber of Phaularpites 

 the carina almost disappears. Lastly, the inner margin of Phaularpites 

 is flat upright, but in Tardarpoceras it is undercut. About this character 

 some remarks follow later. 



The character of subinflation of whorls on the body-chamber makes 

 Phaularpites recall (Edania of the Inferior Oolite (Sonninian) more than 

 any Upper-Lias specimen : the small ribs and general shape also carry on 

 the likeness. As, in the case of foreign species of unknown horizon, the 

 distinction might be important for dating, it is advisable to say a few 

 words. 



Phaularpites recalls mostly (Edania parvicostata (Mon. I.O. Amm. 

 1905, Sup. PI. xxi, figs. 7-9), (E. delicata (figs. 10-12), (E. inflata (figs. 13-15), 

 — the genus having received its name from the subinflate character. 

 Excentrumbilication is not definite in (Edania ; but that is not necessarily 

 a distinction, for such character might be developed in some cases. But 

 the points to notice are the differences in the rib-curve and in the inner 

 margin : the rib-curve in (Edania is more definitely sigmoid or biarcuate, 

 and the inner margin is concave. 



The Inner Margin. The rebated part of the whorl, or the inner 

 margin which passes from the inner part of the lateral area to make 

 junction with the preceding or overlapped whorl, shows a considerable 

 variation of form as between different species, especially of platy cones. 

 In my early work (Amm. TO. ; Q.J.G.S., xxxvii, i88t, p. 593) I pointed 

 -out the differences shown by this character, calling it " The Shoulder," 

 a colloquial term applied in constructional work to any such rebated 

 portion of a plane surface, and, therefore, easily understood. 



In considering the differences in characters of serpenticones and 



