THIRD, OR VERMICERAN BRANCH. 159 
the pile, but the specimen shows distinctly that the form of the adult is more 
compressed than in spiratissimum, with more convergent sides, and it has tuber- 
cules. It is precisely similar to the original of D’Orbigny’s Bonnardi in the Ecole 
des Mines. Ver. Bonnardi is figured by Wright as occurring in the Turneri bed, 
and a much more discoidal form is regarded by him as the true Conybeari and 
figured as such. The great flatness of the whorls and aspect of the whole shell 
in this figure are probably the effect of age. The sutures figured have senile pro- 
portions, the abdominal lobe being of about the same length as the superior lat- 
erals. The specimens figured by Hauer from the Northeastern Alps, and by 
Herbich from Siebenburgen, have more convergent sides and less angular ge- 
nicule than is common in Central Europe. The variety from Luxemburg is very 
like the more discoidal varieties in England. 
Var. planaries. 
Amm. planaries, Fraas, MS. 
Amm. Bonnardi, OppEL, not D’ Orbigny. 
Locality. —Semur, 
The specimen in the Museum of Comparative Zodlogy on the ninth whorl 
had an abdominal lobe one half longer than the superior lateral lobes, and 
inferior lateral saddles one haif deeper than the superior laterals. The in- 
ferior lateral lobes, however, are somewhat longer than the superior laterals, 
and the first and second auxiliaries, which show plainly on the sides, are still 
longer than these. Thus the sutures appear to incline rapidly towards the 
umbilicus, as in Caloceras, but this is a delusion due to the peculiar proportions 
of the auxiliary saddles. The outlines of the superior lateral saddles are covered 
by the involution of the whorl, instead of being in part exposed, as in Conybeari, 
in which last, also; these saddles are apparently broader. The superior lateral 
saddles are divided by a single marginal lobe. 
The pile begin to show senile characteristics on the first quarter of the tenth 
whorl, and on the second quarter of the same whorl the abdomen has suffered a 
diminution in breadth. Throughout the remainder of the volution there is no 
change in the abdomen, but the pile become obsolescent near its termination. 
The external aspect of the adult is similar to Conybeari. 
Only one specimen of this variety occurred in Professor Fraas’s collection ; it 
is placed with Bucklandi, but its position with relation to that species was consid- 
ered uncertain. Professor Fraas considers it a new species under the name of 
Amm. planaries, and the sutures differ greatly from those of the specimen described 
above, though in the form it is more like it than either of them is like Congbeari. 
On the last volution of this specimen the pilee are almost obsolete, the keel more 
prominent, the channels considerably shallower than in the adult. The form of 
the whorl changes somewhat and the sides tend to converge, and the abdomen is 
narrower, but these changes are very slight, and due entirely to the obsolescence 
of the pile. 
This form was at first identified with Bonnardi, D’Orb., but the examination of 
