FOURTH, OR CORONICERAjST BRANCH. 179 



sutures of the nearly adult kridion 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 pilse are nearly obsolescent, with no genicular, 

 thus reverting exactly to the condition of those of Cat. Johmtoni, 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. 1 



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, Hyatt. 



Plate IV. Fig. 1 17. Plate V. Fig. 1-3 a Summ. PI. XII. Fig. 13. 



Coroniceras lyra, Hyatt, Bull. Mus. Comp. Zool., I., No. 5, p. 78. 



Amm. multicostatus brevidorsalis, Quenst., Amm. Schwab. Jura, pi. vi. fig. 4-6; pi. vii. fig. 1-6. 

 Amrn. multicostatus, Hauer, Ceph. Lias d. Nordbstl. Alpen, pi. vii. fig. 7, 8 (not fig. 9, 10). 

 Arietites bisulcalus, Wright, Lias Amm., pi. iii., iv. 



Localities. — Semur, Aalen, Filder, Gmiind, Boll, Tubingen. 

 Var. A. 



Plate IV. Fig. 1, 8, 13-14. 



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 genicular, 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 pilse 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 pilse 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 pilse as in the more advanced stages of Cor. 

 rotiforme. The abdomen on the third whorl becomes flatter, the keel plainer, and 



1 Amm. Schwab. Jura. pi. xv. fig. 2. 



