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es 
4 
FOURTH, OR CORONICERAN BRANCH. i¢9 
sutures of the nearly adult sridion are, however, often quite distinct from those of 
a rotiforme of the same size, but whether this difference is invariable or not, I 
am unable to say. 
The largest specimen in the Museum of Stuttgardt is 470 mm. in diameter. 
On the latter part of the whorl the pile are nearly obsolescent, with no genicule, 
thus reverting exactly to the condition of those of Cal. Johnstoni, var. torus. The 
sides were rounded, channels very shallow, but the keel still prominent. There 
is also a fragment of a very old specimen figured by Quenstedt.! 
His Fig. 5, together with his Fig. 9, quoted above, show that the living 
chambers of the nealogic stages probably exceeded one volution in length, but 
we have not been able to ascertain what they were in adults. 
Coroniceras lyra, Hyarr. 
Plate IV. Fig. 1-17. Plate V. Fig. 1-3a. Summ. Pl. XII. Fig. 13. 
Coroniceras lyra, Hyatt, Bull. Mus. Comp. Zool., I., No. 5, p. 78. 
Amm. multicostatus brevidorsalis, QueNsT., Amm. Schwab. Jura, pl. vi. fig. 4-6; pl. vii. fig. 1-6. 
Amm. multicostatus, WAvEeR, Ceph. Lias d. Nordéstl. Alpen, pl. vii. fig. 7, 8 (not fig. 9, 10). 
Arietites bisulcatus, Wricut, Lias Amm., pl. iii., iv. 
Localities. —Semur, Aalen, Filder, Gmiind, Boll, Tiibingen. 
Var. A. 
Plate IV. Fig. 1, 8, 12-14. 
This is similar to Cor. rotiforme. The bases of the superior lateral saddles are 
very narrow on the sixth or seventh whorl. The bases of the superior lateral 
lobes are proportionally broad, and on the same line with the geniculz, instead 
of on the side, as in other varieties. The superior lateral saddles are pointed, 
but on the eighth whorl they become broader, and are subdivided by three mar- 
ginal lobes. ‘The abdominal lobe is longer than the superior laterals by about 
one third, and the inferior lateral saddles exceed in depth the superior laterals by 
about one fourth. 
Var. B. 
Plate IV. Fig. 2-5. 
This has young with the same rapid lateral increase and deep pit-like um- 
bilicus during the first whorl which was previously observed in Cor. rotiforme. 
The lateral increase is, however, less marked on the second whorl, and_ the 
abdomen begins to become more prominent and rounder. The pile began as 
folds, probably on the second or third quarter of this volution, and the angular 
ridge, which is to become the keel, appeared on the last quarter of this or the 
first quarter of the third volution. The pila never overhang, nor does the abdo- 
men acquire greater breadth than the dorsum, as in the young of Cor. kridion and 
Cor. rotiforme. This stage is skipped entirely, and it is replaced by a stage 
having the same proportions and pile as in the more advanced stages of Cor. 
rotiforme. The abdomen on the third whorl becomes flatter, the keel plainer, and 
1 Ami. Schwab. Jura, pl. xv. fig. 2. 
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