SECOND, OR SCHLOTHEIMIAN BRANCH. 133 
flattened zone. The reduction of the abdomen of course occurs in all species of 
this group, but in other species, except Boucaultiana, it is found only during the 
senile stage. 
Amm. angulatus compressus of Quenstedt may also in part belong to Charmassei, 
since two specimens from the Stuttgardt Museum of this name apparently belong 
to this species only. ‘The envelopment in one of these specimens covers about 
two thirds of the sides of the eighth whorl, and about the same age the pile 
again cross the narrow abdomen, obliterating the median depression or smooth 
zone, and introducing a series of crenulations instead. This is a return to the 
young condition, and indicates the first degradational or clinologie stage. It is 
not intended by this to deny that there are no young which closely approximate 
to the young of Charmassei. On the contrary, some specimens are apparently 
identical in all respects, except the greater flatness of the whorls and the earlier 
period at which involution appears, and the two species are connected by numer- 
ous transitional forms. 
Schlotheimia Boucaultiana, Wiunerr. 
Summ. Pl. XI. Fig. 6. 
Amm. Boucaultianus, D’Orx., Terr. Jurass. Ceph., p. 294, ples 
Schlot. Boucaultiana, WAn., Unt. Lias, Mojsis. et Neum., Beitr., IV. p. 196. 
4iigoc. Boucaultiana, Wricur, Lias Amm., p. 327, pl. xviii. fig. 1-4. 
Locality. — Semur. 
This remarkable species differs from Le/gneletii in about the same manner that 
the latter differs from Charmassei, in other words, it is more involute than Leigne- 
dei at the same age; i.e. on about the seventh or eighth whorl at least three 
fourths of the sides are hidden. The pilx are not so coarse as in that species, 
and the abdominal channel is obliterated at an earlier age and is succeeded by 
crenulations caused by the pila. The sutures differ considerably. The specimen 
examined was one of D’Orbigny’s types. The same transitional forms which lead 
into Leigneletii also lead into other more compressed and more involute forms 
which are transitional to the true Boucaulliana. They differ from Leigneletti: only 
in the suppression of the tuberculated pile, and a general tendency toward obso- 
lescence of the pile. on the sides. 
Schlotheimia D’Orbignyana, Hyarr. 
Amm. Charmassei (pars), D’OrB., Terr. Jurass. Ceph., pl. xcii. (not pl. xci.) 
Locality. — Semur. 
This species has depressed pile and resembles'closely Boucaulliana, but is not 
so involute. It is in fact, as described by D’Orbigny, an extreme modification of 
Charmassei, with excessively compressed whorls, and acquiring in the clinologic 
stage a subacute abdomen. It resembles more closely Schlot. ventricosa of Wahner 
than it does any other species, but it is even more compressed and more like 
Charmassei in the adult stage than that species. D’Orbigny’s figure is that of an 
old shell; the adults are less acute and more like Oharmassei or Leigneletii. 
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