398 S. S. Buchnan — On Jurassic Ammonites. 



3 inches 4 lines in diameter, has four whorls at least. Wright's 

 serpentinus at the same diameter has barely three. Talking the 

 diameter of Eeinecke's figure as = 100, the breadth of the outer 

 whorl is 29-6, whilst taking the same diameter on Wright's figure 

 (3 inches 4 lines), we find the breadth of the outer whorl at that 

 size is 40-7. I think it is therefore clear that Sowerby's Am. 

 falcifer is not Eeinecke's Am. serpentinus. 



Haepoceras elegans (Sowerby). 



1815. Ammonites elegans, Sowerby, Mineral Conch, vol. i. table 94, upper figure. 

 1884. Harpoceras hicarinatum, Wright (nonZieten), Lias Ammonites, Pal. Soc. 1884, 

 plate 82, figs. 9 and 10 (non 11). 

 Non Am. elegans, Young and Bird, non Harpoceras elegans, "Wright. 



Sowerby describes his species in the following terms : — 



" Sjpec. CJiar. Involute, much depressed, acutely keeled : volutions 

 about three, inner ones about two-thirds concealed ; radii twice 

 curved, numerous, equal ; keel distinct, entire ; aperture acutely 

 triangular ; internal angles truncate. 



" A delicate species with a thin shell ; thickness about one-sixth 

 of the largest diameter ; it gradually lessens towards the edge, which 

 is rather obtuse, with a sharp keel placed upon it. The septa are 

 tolerably close with their sinuous margins much plaited : the 

 siphuncle slender within the keel." 



Sowerby's type-specimen is not in the British Museum collection, 

 and so unfortunately we cannot refer to it ; but although the species 

 has been much misunderstood, I think that if the figure and the 

 description be accurately studied, we shall be able to arrive at definite 

 conclusions about it. One thing is perfectly certain, that the Am. 

 elegans of Young and Bird is not Sowerby's elegans. Dr. Wright 

 has figured on plate 63, Harpoceras elegans, Sowerby, but has 

 corrected this in his text, page 447, to Yovng, and he further states : 

 " Some authors refer this species to Am. elegans, Sowerby, but none 

 of the specimens I have examined correspond with Sowerby's 

 figure, which does not appear to be a Lias shell at all." However, 

 on p. 462 he places Am. elegans of Sowerby as a synonym of Harp. 

 hicarinatum, and in this matter I think he was so far correct that I 

 think his Harp, hicarinatum, plate 82, figs. 9, 10, are really Sowerby's 

 Am. elegans, and certainly not Am. hicarinatus of Zieten, plate 15, 

 fig. 9, which has a far smaller centre. 



Dr. Haug, on page 680 of his Beitrtige Monog. Harpoceras, is 

 mistaken in supposing Dr. Wright to have figured. Sowerby's Am. 

 ■elegans on plate 63, and Dr. Wright himself corrects this. Sowerby's 

 Am. elegans does not belong to the group of Am. opalinus as Dr. 

 Haug has placed it, though undoubtedly Am. elegans, Wright, does. 

 Therefore we have this position : — The Am. elegans, Sowerby, I 

 consider to have been figured again by Wright as Am. hicarinatus, 

 and not 'to be Zieten's Am. hicarinatus, and that it is also a distinct 

 species in itself. Further, that it belongs to the restricted group of 

 Am. falcifer, which is now erected into a genus, and therefore must 

 be called Harpoceras elegans, Sowerby. On the other hand, the 



