ert 
FOURTH, OR CORONICERAN BRANCH. 17 
First SuBSERIES. 
Coroniceras kridion, Hyarr. 
4 
| Plate Ill. Fig. 2, 3. Summ. Pl. XII. Fig. 9. 
Amm. kridion, Ziev., Verst. Wiirt., pl. ili. fig. 2. 
Amm. kridion, HAvUER, Ceph. Nordostl. Alpen, pl. iii. fig? 4-6. 
Localities. — Semur, Stuttgardt, Balingen. 
| 
! 
The pile were already visible on the first part of the third whorl, but when 
| they began could not be ascertained. On the first quarter of the third whorl 
the flattened abdomen of the younger volutions became more elevated, and the 
keel was introduced. The keel continued to increase in prominence thereafter, 
but the channels, which are faintly visible on the fourth whorl, only broaden out, 
and do not sensibly increase in depth, after they reach the last part of the fifth 
volution. 
The form acquired on the third or fourth whorl is carried throughout life, the 
sides curving evenly from the dorsum to the abdomen; the abdomen is elevated, 
the pile are either overhanging or slightly tuberculated on the latter part of 
the third whorl, but very soon the curvature becomes equal and the tubercula- | 
tions disappear, though the genicule sometimes remain very prominent even on | 
casts. There are three specimens of this species in the Museum of Stuttgardt, 
| the exact position of which, with relation to Bucklandi, is considered uncertain 
by Professor Fraas. The young in all these specimens are smooth, and precisely 
| similar to the young of the specimens from the Angulatus bed, from which the 
adults, however, differ slightly. The tubercular processes on the casts, as in all 
other specimens of this species, are blunt, and covered smoothly by the shell, not t 
protruding into spines. The specimens in the Bucklandi bed have longer, 
stouter whorls, with different sutures, but these differences are not sufficient to 
separate them; they are probably closely allied direct descendants. 
Oppel claimed to have had the original of Zieten’s description, and, according 
to him, it is a species like Conybeari, which is found with and under Bucklandi. | 
The above is the only species answering to this description and agreeing with i 
Zieten’s figure in having tuberculated pile, slightly divergent sides, a raised 
abdomen, and prominent keel. There are no channels in Zieten’s figure, but his 
specimen was young, and even in the full-grown fridion they are very shallow. 
} Two adults and three young specimens from Mohringen, labelled Bodleyi (No. 
3977), are in the Museum of Stuttgardt, from the Angulatus zone. The casts 
appear to be identical with Amm. Caprotinis D’Orb., but the apparent tubercles | 
were merely covered smoothly by the shell, and not continued out into points. 
Besides these specimens there is a fossil from Filder (No. 8978), which is precisely 
; like Zieten’s figure,! and confirms these identifications. 
Though there is close approximation in the characteristics of the young in 
most forms, there are sometimes differences. The young of the normal forms 
sinh Rint 
1 Zieten’s original T was not able to see ; it could not be found in the Museum at Munich during 
TH Vaait. 
