fun. 
US j. Buckman, 1844. 
ultell 
Ammonites 
CEPHALOPODA Ammonites cultellus 
J. Buckman, 1844. 
Original description 
(1844. — Op. cit., pp. 103 and 89). 
« À cultellus, Tab. 12, f. 4 and 5. — Keel very sharp, volutions 4 to 5, half concealed, 
outer whorl broad, somewhat thickened at its anterior side, and gradually thinning off 
towards the keel, thus presenting a sharp edge after the manner of a knife, ribs slight, 
somewhat distant. Diameter about 3 1/2 in., thickness 1/2 in. 
« LocaLrry. — With the two preceding [A. Colesi, A. accipitris]. Very common. This shell 
varies from 1/4 in. to about 4 in. diameter, and is frequently covered with a thin coating of 
iron Pyrites, when the specimens are glossy and much the colour of gold ; in many speci- 
mens, this has become decomposed, and the surface of the shells present a thin layer of the 
red or yellowish-red per-oxide of iron. » 
[P. 89] « L. S. Cleeve and Railway cuttings, vale of Gloucester ». 
OBSERVATIONS 
Although figs. 4, 5, of Plate XII were both placed under the name A. cultellus, the 
description (except the diameter which is obviously incorrect) as well as the signification of 
the name only fits the specimen depicted in fig. 4. This howewer is the same species as 
Quenstedt had in the previous year named Am. oxynotus, but he did not figure it, he only 
give a reference to an unsatisfactory figure. But as the species has been for so many years 
known by his name, and as there is the shell depicted in fig. $ also bearing the name 
cultellus, it seems desirable to say that fig. 5 shall now be taken as the amended holotype 
of Am. cultellus. 
Fig. $ may be thus described : whorls much compressed, only slightly gibbons, thickest 
about the middle, nearly smooth — there are only obscure traces of ribs whose direction in 
regard to a straight line is shown in the fig. T.? The periphery is subacutly fastigate, À, 
having an edge but no distinct carina, and no hollow carina. The umbilicus is small, inclu- 
sion of whorls being 3/4. The inner margin of whorls is convex and somewhat 
overhanging. The septal margins are simple, the peripheral lobe is shorter than the superior 
lateral, which is broad, short, and situated rather close to the periphery. 
This species is both specifically and generically distinct from 4m. oxynotus (Oxynotoceras). 
It differs particularly in the suture-line which is more of the Asteroceratan pattern. There is 
really no genus to which this species can be satisfactorily assigned at present, but to 
temporarily place it in Asferoceras seems to be desirable. 
Locality and Horizon. The « two preceding » with which À. cultellus (fgs 4, 5) is saïd 
to occurr evidently refers to À. accipitris and À. Colesi, though they are not exactly the 
two preceding in the descriptions. The Railway cutting as Lansdown Station, Cheltenham, 
is known to have furnished many specimens of the form depicted in fig. 4. The A. cultellus 
(fig. 5) has the decomposed iron-pyrites colour referred to, found also in specimens like 
fig. 4. Probably therefore it came from the same horizon, and it may thus be recorded : — 
Lower Lias, Upper Sinemurian (zone of Am. oxynotus ?) near Cheltenham, Gloucestershire. 
Summary. 4. cultellus (PI. XII, fig. 4) — Oxynotoceras oxynotus Quenstedt. 
» » (PL XIL, fig. 5) — Asteroceras ? cultellus J. Buckman. 
1904. S. S. Buchman. 
25° 
