FOURTH, OR CORONICERAN BRANCH. 183 
Wright’s visit to his collection. Quenstedt’s huge specimen, 700 mm. in diam- 
eter, noted above, is described’ as having the pile: obsolescent near the termina- 
tion of the last volution, and the keel as showing but little above the almost 
obsolete channels. This, therefore, is an extreme example of senile degeneration 
in the clinologic stage, but it has not yet reached the nostologic stage. 
Coroniceras Gmuendense, Hyarr. 
Plate V. Fig. 4-9. Plate VI. Fig. 1, 2. Summ. Pl. XII. Fig. 14. 
Amm. Gmuendense, OrpeL, Der Jurafor., Wiirt. Jahreshf., XII. p. 200. 
Amm. Brooki, Zrev., Verst. Wiirt., pl. xxvii. fig. 2. 
Aster. tenue, Hyatt, Bull. Mus. Comp. Zodl., I. No. 5, p. 79. 
Ariet. Crossi, Wrigut, Lias Amm., p. 283, pl. x. fig. 1, 2. 
Localities. — Semur, Gmiind, Gdppingen, Aalen, Aargau. 
The adults of this species are readily distinguishable from Cor. lyra by the 
smaller size of the whorls, the characteristics of the sutures, the extreme narrow- 
ness of the abdomen as compared with the dorsum, and the broad, shallow chan- 
nels. The keel is more prominent also than in Cor. lyra, and the pile end very 
abruptly with geniculz or pseudo tubercles. This peculiarity is observable on 
the latter part of the sixth whorl, and the bending forward of the geniculs, as 
they rise on the narrow abdomen, is hardly observable on the cast until after the 
completion of the seventh whorl. On the eighth volution the genicule become 
less prominent on the cast, and the depressed genicule and pile: form a single 
arch slightly interrupted by the tubercular aspect of the former. These charac- 
teristics are not altered when the shell is present, but have about the same ex- 
pression as upon the cast. The genicule on the seventh whorl, in one specimen 
examined, are prominent, and their forward bend plainly observable, though 
without tubercles. 
The abdominal lobe is broad and deep (Plate V. Fig. 5). The superior lateral 
saddles and lobes are nearly obsolete, the inferior lateral lobes and the first aux- 
iliary saddles are but slightly developed. On this account the inferior lateral 
saddles, which are of about the usual size, acquire remarkable prominence. 
We have already noticed, in variety C of Cor. rotiforme, a tendency towards the 
suppression of the superior lateral saddles, and here it is actually carried out. 
The marginal lobes and saddles of the superior laterals, however, remain on one 
specimen from Aargau, but on one from Semur only the inner of the three sad- 
dles is of noticeable size. These characteristics are present in the adults of this 
species, and consequently are not due to old age. 
On the latter part of the eighth whorl the pile lose their tubercles, (Plate V. 
Fig. 5,) and the genicule become almost obsolete, being reduced to curved con- 
tinuations of the depressed arched pilx&, which are most prominent at the um- 
bilical shoulders. The channels continue to be very well defined, though much 
shallower, (Plate V. Figs. 8, 9,) and channel ridges are preserved until the first 
quarter of the tenth whorl. On the second quarter of this whorl the pile are 
1 Amm. Schwib. Jura, p. 115. 
