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FOURTH, OR CORONICERAN BRANCH. 185 
lobes and saddles are, however, serrated, not deeply divided by the marginal 
lobes, as in the last named species. The abdominal lobe is one half longer than 
the superior laterals, and the inferior lateral saddles exceed the superior laterals 
in the same proportion. 
A fine suite of these specimens exists in the Museum of Stuttgardt, showing 
the variations described above. Some are very decidedly ‘planicostan in aspect, 
but not more so than other specimens of Coroniceras, in which the keel becomes 
entirely suppressed, and the abdomen is crossed by the pilx. Young specimens 
from Behla pass through stages which repeat exactly the characteristics of Cor. 
kridion when considerably older and perhaps full grown. One of these is labelled 
capraries, Fraas, planicostan variety ; another lot of three specimens is named 
Danulicus, on account of their thick whorls and pile. A large specimen from 
Gmiind, on the last part of the last whorl, has all the characteristics of the stout 
English specimens of var. Gaudryi, Reynés. There is also a fragment of a much 
older shell, the dorso-abdominal diameter of the whorl being 60 mm., which has 
similar characters. The channels are, however, very broad and shallow, and the 
keel also low and broad. 
Since the above and the description of var. Gaudryi were written, I have 
found in the collection of the Museum of Comparative Zodlogy English speci- 
mens of this species exhibiting the young. In these, for one or two volutions, 
the whorls are smooth, then obscure tubercles or swellings begin to appear upon 
the sides, which elongate into folds on the third whorl, and become distinct pile 
on the latter part of this whorl or the first quarter of the fourth. The external 
resemblance to the young of Cal. Johnston’ is complete in the pilx, the com- 
pressed or embryonic form of the whorl, and the absence of a keel; the sutures, 
however, do not appear to be similar. Even on the early portions of the third 
whorl the abdominal lobe is quite long, the superior and inferior lateral lobes 
exceedingly short, and the corresponding saddles of equal depth. From this 
time the complication consists in the crenulation, or rather serration, of the mar- 
gins, and the slow increase of depth in the superior lateral saddles; the other 
saddles and lobes remain about what they were at first with regard to their 
proportions. The keel is perceptible as a slightly raised siphonal line on the first 
quarter of the fifth whorl or last of the fourth. In the first of this stage, the 
abdomen, pile, and form of the whorls are similar to those of the adult of Cor. 
kvidion. On the fifth volution, however, the abdomen becomes flatter, the ge- 
nicular band of the pilze more abrupt, and finally tuberculated, and the hitherto 
divergent or gibbous sides flatter and slightly convergent. 
The young figured by Quenstedt’ are questionable. They are more com- 
pletely pilated than is usual in the species, and the form of the whorl is quite 
different. We doubt the correctness of the identification. 
1 Amm. Schwib. Jura, pl. xi. fig. 15-17. 
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