FOURTH, OR CORONICERAN BRANCH. 189 



Coroniceras Hungaricum, Hyatt. 



Amm. Hungaricus, Hauer, Ceph. Lias Nordostl. Alpen, pi. iv. 



The figure of this species possesses the exact form and characteristic of the 

 bisulcatus series. It has similar unshapely geniculce thrown out beyond the 

 edges of the abdomen, giving the whorl a peculiar angular and squared aspect; 

 the genicular also interrupt the channel ridges, and the keel, though well de- 

 veloped, is almost counter-sunken in the deep channels. The pilse are very 

 straight in Hungaricum, and have no tubercles; the form is also somewhat more 

 compressed than in bisulcatus. The sides also are perfectly flat and parallel, and 

 the depressed abdomen and nearly equally flattened dorsum are of the same 

 breadth, the whorl in section being a parallelogram with the sides about one 

 fifth longer than the transverse diameter. The specimen figured by Hauer was 

 135 mm. in diameter, and consequently the complete shell must have reached a 

 much larger size, since his specimens exhibit no signs of the approach of senility. 



Third Subseeies. 

 Coroniceras latum, Hyatt. 



Plate III. Fig. 19-23 a. Summ. PI. XII. Fig. 16. 



Coroniceras latum, Hyatt, Bull. Mus. Comp. Zodl., I., No. 5, p. 77. 

 Amm. Bucklandlpinguis, Quenst., Amm. Schwab. Jura, pi. ix. fig. 3? . 

 Locality. — Semur. 



Many of the young of this species, Plate III. Fig. 22, 23, have large tubercles 

 early on the second whorl, and on the third these become elongated into tuber- 

 cular folds. On the fourth, or on the latter part of the third volution, the inter- 

 vals between them increase, and they become true pilre. In other specimens, 

 Plate III. Fig. 19, the pilse are acquired as in rotiforme, Plate III. Fig. 5, and there 

 is also in many specimens, Plate III. Fig. 22, a close resemblance to the adult of 

 Cor. bidion, Plate III. Fig. 3. The keel appears on the first quarter of the fourth 

 whorl, but at the latest stage observed on the second quarter of the fifth volu- 

 tion of a cast the keel was still very thin, sharp, and but slightly elevated. The 

 channels, however, though very shallow and broad, had acquired lateral ridges. 

 On the second whorl the breadth of the abdomen is very much increased by the 

 development of tubercles, the sides becoming exceedingly divergent in some 

 specimens, and the abdomen gibbous. On the fourth whorl the central area 

 begins to become depressed, Plate HI. Fig. 23, but the abdomen on either side 

 retains its remarkable gibbosity. In correlation with this and with the narrow 

 dorsum, the abdomen is never entirely covered by the succeeding whorls, but has 

 an exposed border on both sides. On one specimen, Plate III. Fig. 22, 23, both 

 the pilos and genicular are double ; in others, the pilae are single and the genic- 

 ulse are double ; on another, the duplication of the geniculae ceases on the third 

 quarter of the fourth whorl, with the exception of one single genicula on the last 

 quarter, which is double. One cast of the second variety was very much broader 



