ag its 
THIRD, OR VERMICERAN BRANCH. 139 
the usual stout smooth whorl of the young of Johnstoni. Quenstedt places them 
with /aqueus, but this, we think, is a mistake, arising from not giving proper 
weight to the characteristics of the nealogic stages. 
The presence of this form in the North German basin is worthy of remark, 
since it is a degraded variety. The transitional keelless varieties uniting this 
species and Johnstom would have been considered distinct under the name tortie, 
while the keeled forms would have been separated and designated as a distinct 
species, but for the fact that similar variations are also represented within two 
other species, Cal. Liasicum and Nodotianum. It is evident from this, that the 
keel in Caloceras has not become an hereditary character, but is a morphological 
equivalent in varieties of different species. 
Caloceras Liasicum. 
Amm. Liasicus, D’OrB , Pal. Fran. Ceph., I. pl. xlviii. 
Amm. Liasicus, HAvER, Ceph. Lias Nordostl. Alpen, pl. iii. fig. 1-3. 
Amm. sironotus, Qumnst., Handb. Pet., p. 482, pl. xxxvii. fig. 1; and Die Amm. Schwab. Jura, p. 23, pl. i. 
fig. 21. 
Amm. laqueolus, ScuLON., Paleontogr., XIII. pl. xxvi. fig. 1. 
Aiyoc. laqueolus, Wricut, Lias Amm., p. 315. 
4éyoc, Liasicum, Wrieut, Ibid., pl. xv. fig. 1, 2; pl. xvi. fig. 1, 2. 
Aigoc. tortile, Wrieut, Ibid., pl. xv. fig. 10, 12. 
Ariet. Liasicus, WAu., Unt. Lias, Mojsis. et Neum., Beitr., VI., 1887, pl. xx. fig. 1-5. 
Localities. — Semur, Bristol. 
A large specimen in the Tiibingen collection, about 100 mm. in diameter, 
shows by comparison with D’Orbigny’s figure that sdronotus, Quenst., is prob- 
ably identical. One specimen at Semur retained very gibbous sides and broad 
abdomen to a diameter of 175 mm., and then formed an elevated abdomen with- 
out acquiring a true keel as figured by D’Orbigny. Another shell had reached 
the diameter of 260 mm., but no true keel was formed, though old age began to 
show its approach in the obsolescence of the pile. In D’Orbigny’s collection 
these very broad forms stand side by side with the narrow one figured by him, 
which is identical with sironotus, Quenst. D’Orbigny’s original has the keel as 
well developed at a diameter of 100 mm. as the broad variety at a diameter of 
250 mm. A comparison of the young with the young of fortile showed that they 
are closely allied by their development. No constant distinction exists, except 
that Liasicum is usually a stouter shell, and has about the same relation to ¢ortile 
that the stouter forms of carusense in the Upper Bucklandi bed have to those of 
the same name in lower beds. Wihner’s work upon this species gives figures of 
the young, and exhibits a close alliance with Ca/. Johnstoni. The keel appears 
in his Figure 3b, in a small but probably full-grown specimen, but no channels 
are noted in his figures or description. 
The extraordinary series of forms discovered by Neumayr and Wihner in 
the Northeastern Alps enable us to give the following list of species, arranged 
in subseries. 
