310 
INFERIOR OOLITE AMMONITES. 
PI. LIV, with suture-line in situ; while figs. 4, 5, of the same plate illustrate a 
very fine specimen of the form j3, with its hpllow carina well-preserved. 
Figs. 1 and 2, PI. LV, give the suture-line and the radial curve of the strige 
of this specimen. 
DoESETENSiA LiosTEACA, 8. Buckman. PI. LIII, figs. 11 — 16; PI. LV, figs. 3 — 5; 
PI. LVI, fig. 1. 
1886. Ammonites Tessonianus, Quenstedt (non d'Orligny). Schwabischen 
Ammoniten, pi. Ixiii, fig. 7. 
Discoidal, compressed, hollow-carinate. Whorls broad, ornamented with fine, 
arcuate, ventrally-projected strise. Ventral area undefined, furnished with a 
large hollow carina. Inner margin upright until last half-whorl, then somewhat 
sloped. Inclusion nearly whole whorl, except when body-chamber present. 
Umbilicus graduated, small, but increasing in last half-whorl. 
Herein I have combined three forms : 
a. A rather wider-centred form than that shown in PI. LV, fig. 3. It seems 
to be exactly intermediate between this species and " subtecta /3," I have not 
thought it necessary to figure a specimen, especially as the form is shown by 
Quenstedt (loc. cit.). 
(5. (PI. LIII, figs. 11—15 ; PI. LIV, figs. 3, 4.) This may be regarded as the 
type — " the smooth shell " — hence the name. 
y. (PI. LV, fig. 5 ; PI. LVI, fig. 1.) A form which has obscure undulate ribs. 
In the smaller specimen, where they succeed a striate period, they would appear 
to be due to reversion. 
The form marked /3 is commoner than the others. Specimens very con- 
siderably larger than the figured example are in my collection, but their state of 
preservation is indifferent ; and, besides, the selected fossil is fairly complete. 
The core bears the plain impression of the rim of the lower part of the mouth as 
shown in the drawing, indicating that the body-chamber was half-a-whorl in 
length. 
The largest example in my collection is eight and a half inches in diameter, 
but then it has practically no body-chamber. When complete it probably 
measured eleven inches across, as against barely seven inches in the case of the 
figured specimen. 
The Humphriesiambm-zone of Oborne, Dorset, has yielded the examples I 
possess. It is not a common species. 
Fig. 13, PI. LIII, shows the various phases of the inner whorls of this species. 
