154 GENESIS OF THE ARIETID. 
defined, though the first old age stage is shown to have begun by the flatness and 
inclination of the sides in the section given by Wiihner on Plate XXIV. Fig. 7 e. 
Cal. (Ariet.) Grunowi (Hauer), Wiih ,* resembles closely centauroides, but is evi- 
dently even less advanced, since the development of the keel is less marked, and it 
is doubtful if it ever have channels. The two species mentioned above, centau- 
roides and Grunowi, as described by Wiihner in their younger stages, have sutures 
which differ from the similar forms described by Canavari in his Fauna of the 
Lias, so often quoted above. The sutures are unquestionably arietian, having 
deep narrow abdominal lobes and lateral sutures like those common in Caloceras. 
The sutures, form, and characteristics of Aegoc. centauroides, Canavari, figured on 
Plate V., ally it closely with the species figured on Plate VII. as Acgoc. Listeri? 
The extraordinary species figured by Neumayr, Cul. (digoc.) Sebanum, Pied. 
is supposed by him to be a species with young, like those of the schlotheimian 
series. It is apparently, if the figures are accurate, a keeled caloceran form, with 
prominent angular genicule in the young, and we entirely agree with Wihner 
that it cannot be allied to Schlotheimia. Such a shell might be traced either to . 
Cal. tortile, or almost any species of Caloceras having an immature keel and well 
defined pila. The characteristics suggest a subseries of which the tuberculated 
Cal. laqueoides of the Angulatus bed of Wiirtemburg would be also a member. 
Geyer, in his “Lias. Ceph. d. Hierlatz b. Hallstadt,” gives three species of 
small size, Cal. (Arietites) sp. indet. aff. Nodotianus, D'Orb., Plate TIT. Fig. 16 ; Cul. 
(Ariet.) doricus, Plate IIL. Fig. 3; and Oal. ( Ariet.) raricostalus. This is a fauna 
mostly composed of dwarfed forms of species, which there lived under unfavorable 
conditions, as did those of Spezia in the south. 
Canavari, in his Unteren Lias v. Spezia, gives Cad. ( Ariel.) Corregonense, Fig. 
12-15, which seems tobe the young of a stout variety of Johnstoni ; Cal. (Arict.) 
retroversicostatus, which may be young of Cad. salinarium described by Wihbner from 
the Northeastern Alps; Cul. (Afgoc.) helicoideum, Plate V. Fig. 7, tortwosus, Fig. 8, 
and carusense, Fig. 10, all belonging apparently to the same species, most likely 
young or dwarfs of the last named ;* and Cad. ( Arve.) raricostatum, Fig. 9, 1s prob- 
ably the young of some Caloceran species, since the drawing does not have the 
aspect of raricostatum. 
VERMICERAS. 
In this genus we find several characteristics which were merely specific or 
varietal in Caloceras, becoming established as an integral part of the growth, and 
furnishing good generic characteristics. 
1 Mojsis. et Neum., Beitr., VI. pl. xxv. fig. 2, 3. 
2 The species accompanying this one, figured on the same plate as Tropites ultratriasicus, Arielites Cam- 
pigliensis, ligusticus, and discretus, are all apparently true Tropites with tubereulated and coronate whorls in 
the earlier nealogic stage, and acquiring a keel and pilee while still retaining the coronate depressed form of 
their triassic radical, Tropites subbullatus, The sutures as figured are similar to those of the adult of 
Tropites Jokeyli, as given by Hauer, Ceph. d. Hilst. Schich., Denks, Akad. Wien, IX., 1855, pl. iv. 
8 Unterst. Lias, Abhandl. geol. Reichsans., VII. pl. iv. fig. 2-4. 
4 Referred by Canavari to the young of proaries in Mem. della Carta Geol. d’ Italia. 
