S. S. Buckman—On Jurassic Ammonites. 201 
Harpoceras STRANGEWAYSI (Sowerby). 
1822. Ammonites Strangewayst, Sow. Min. Conch. pl, 254, figs. 1 and 3. 
1885. Harpoceras serpentinum, Thompson (non Reinecke), Upper Lias; Journ, 
Northampt. Nat. Hist. Soc. vol. ii. p. 309, pl. 1, fig. 1. 
Discoidal, compressed, hollow-carinate. Whorls flattened, orna- 
mented with genuine sickle-shaped ribs, which, though less con- 
spicuous in size on the body-chamber, are there more distinctly 
bent. Ventral area marked by the prolonged forward sweep of the 
ribs, and surmounted by a well-marked hollow-carina. Inner margin 
almost upright, neither concave nor convex. Umbilicus shallow 
and open. Inclusion, with the body-chamber present, one-third. 
Termination of mouth-border partly visible, showing that it is plain, 
and curved like the ribbing. Aperture, oblong. 
The above, taken from Mr. Walford’s specimen, differs in some 
particulars from Sowerby’s description ; but then neither Sowerby’s 
figure, nor his description, agree with the original specimen. The 
umbilicus is drawn considerably too large; the inner margin— 
“oblique flattened surface which forms the inner edges of the 
whorls ”—which Sowerby emphasizes so particularly, is by no means 
slanting, but is nearly upright, and the sectional view which he 
_ gives is quite incorrect. The ribs, too, are not drawn with sufficient 
bend ; they are truly of the shape of a sickle, with the inner portion 
quite straight and a marked bend at the middle. The indications of 
suture-lines are correct enough in Sowerby’s figure, and his specimen 
shows that the lobes are exactly those of Harpoceras, as I described 
these in my former communication (p. 397). 
Harpoceras Strangewayst differs from Harp. faleiferum by its 
umbilicus being much more open—about one-fourth larger—its ribs 
not quite so strongly bent, and its inner margin almost upright 
instead of being undercut. Individual specimens of this species 
seem to differ in the coarseness of their ribbing. Sowerby’s example 
is more coarsely ribbed than his drawing would lead us to expect. 
Mr. Walford’s specimen came from the “ Fish-bed, Upper Lias, 
Byfield”; Mr. Thompson sent me a specimen from Bugbrook ; and 
I have a poor example from Trent near Yeovil ; Sowerby’s specimen 
came from Ilminster. The species seems to be unknown on the 
Continent. 
HILpocERAS SERPENTINUM (Reinecke). 
1818. <Argonauta serpentinus, Reinecke, Maris protogei, figs. 74, 75. 
1867. Ammonites serpentinus, Meneghini, Monogr. calc. rouge ; Paléont. Lombarde, 
4e série. Plate iti. fig. 1. 
1885. Hildoceras serpentinum, Haug, Beitr. Mon. Harpoceras; Neues Jahrbuch 
fiir Mineral. Beil.-Bd. iii. p. 643. 
I discussed this species in my previous communication (p. 396), 
pointing out wherein it differed from a species to which this name 
had been erroneously applied. I was uncertain, then, as to its 
genus, because I had not a specimen; and Am. Strangewayst being 
given as a synonym misled me. 
