THIRD, OR VERMICERAN BRANCH. 147 
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33 24 
Fig. 23, 24. Views from the side and abdomen of Cal. aplanatum. 
Bean, and were said to have been found in the Lower Lias. Their young, seen 
from the side and only in the umbilicus, have the peculiar pile and general 
aspect of raricostatus, with similar rotund sides and fine closely set pile. 
Cal. (Ariet.) prespiratissinum, Wih.,* has distinctly caloceran sutures and pile 
without genicule. It develops a keel at an early stage, and has a subquadragonal 
whorl in the adult with slight channels. It is a close morphological equivalent 
of the Vermiceran-like variety of Cal. daqueum of Central Europe, if not identical 
with it, and is certainly, as stated by Wihner, transitional to Ver. spiratissimum. 
Wiihner’s figures prove that Cal. proaries is a form with late development of a 
keel, the exact equivalent of Cal. Nodotianum in the Central European province. 
Wiihner’s full series of young and adults,* and Neumayr’s senile specimen figured 
in Unterster Lias,? show that the young of Cal. proaries (Plate XXX. Fig. 7) resem- 
ble very closely the adult stages of Psi. sublaqueum, Wah. (Plate XXX. Fig. 4), 
Cal. Johnstoni (Plate XVI.), and Cal. (Psil.) orthoptychim, Wah. (Plate XXVII. 
Fig. 2), and the unnamed form figured on Plate XXVIL Fig. 3. Cal. (Psil.) 
gomoptychum, Wih.,* has the same compressed whorls as in the more advanced 
stages of proaries, and appears to be intermediate between that species and Cul. 
cycloides. The sutures agree with those of proaries. We venture to differ from 
Wiihner, who associates this species more closely with Cai. Sebanum of the Pla- 
norbis bed. The apparently intermediate aspect and characteristics seem to 
have been inherited at an earlier stage than in proaries, but not quite so early 
as in cycloides, if one can use figures for arriving at such conclusions. Cai. (Ariet.) 
1 Mojsis. et Neum., Beitr., V. pl. xxi. 2 Tbid., IV, pl. xxviii-xxx. 
8 Abhandl. geol. Reichsans.,, VIE. pl. xxviii. 4 Mojsis. et Neum., Beitr., IV. pl. xxvii. 
