THIRD, OR VERMICERAN BRANCH. 1438 
is sometimes identified with Amm. Liasicus in Germany, but that species has a 
form more like Johustoni, a larger keel, and entirely distinct sutures. 
A specimen from Aldingen, in the Museum of Stuttgardt, shows an entirely 
smooth senile whorl, precisely similar in form to that described above in the 
collection of the Museum of Comparative Zodlogy, though it is not half the size, 
the diameter being 103 mm. Another from Vaihingen had a living chamber still 
incomplete, though nearly one and a half volutions in length. On the latter 
part of the eighth volution in this specimen the sides began to become flatter 
and convergent, and on the ninth and tenth volutions the form was subtrigonal, 
the channels absent, the pile still prominent though obsolescing, and the keel 
reduced to a raised line; diameter, 163 mm. Another, of nearly the same size 
as Hauer’s figure of Amm. spiralissimum, agreed closely, the sutures also being 
identical. The form of the whorl is, however, slightly more flattened laterally. 
It belongs to the large variety of carusense, and is found, according to Hauer, 
with Conybeari, roliformis, and bisulcalus, in the “ gelben kossener Schichten of 
Enzesfeld.’ A specimen from Elwangen, labelled Amm. torus, in the Geo- 
metricus zone, exhibits all the characteristics of the large specimen described 
above. It has larger and stouter whorls and pilx than the specimens described 
from the Lower Bucklandi beds, though the sutures and other characteristics 
are similar. A specimen of this variety from Aalen also occurs in Professor 
Quenstedt’s collection at Tiibingen, with larger and more prominent pile than 
usual. 
The young and old stages of this species at Semur and elsewhere are usually 
identified either as torus, or tortilis, or Johnstoni, because of the resemblances of 
the stages of development and senility in the different species of this series. 
Caloceras longidomum, Hyarr. 
Amm. longidomus, QueNstT., Amm. Schwab. Jura, p. 50, pl. vi. fig. 1, 2. 
Amm. longidomus eger, QuENsT., Ibid., pl. vi. fig. 3. 
This species, as described and figured by Quenstedt, cannot be classified 
with certainty. Not having seen specimens unquestionably referable to the 
species, we cannot positively decide as to its true affinity. It is, according to 
Quenstedt’s description, a more immature or primitive form than spzratissimum, 
since he alludes emphatically to the resemblances between the young and 
Psiloceras. He also states that the young are closely allied to the young of 
spiratissimum. This evidence seems to conflict, but the sutures, their backward 
inclination, and the fact that the abdominal lobe, though longer than the supe- 
rior laterals, is only slightly longer, the not very prominent and curved pile of 
Quenstedt’s figure, the broad keel and slight channels, and the somewhat com- 
pressed form of the older whorls, are all characteristics similar to those of caru- 
sense. It may be a variety of carusense larger than the French, and becoming 
senile more slowly. The curved pile are not like dagueum, and the cylindrical 
whorl and tendency of the pil to cross the abdomen in the young also suggest 
connection with carusense. 
