154 GENESIS OF THE ARIETID.E. 



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 Wahner on Plate XXIV. Fig. 7 e. 

 Cal. [Arid.) Grunowi (Hauer), Willi, 1 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 Wahner 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 Aegoc. Lister/'. 2 



The extraordinary species figured by Neumayr, Cal. (JEgoc.) Sebanum, Pich.. 3 

 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 genicular in the young, and we entirely agree with Wahner 

 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 pilae. The characteristics suggest a subseries of which the tuberculated 

 Cal. laqiieoidcs of the Angulatus bed of Wiirtemburg would be also a member. 



Ge3er, in his "Lias. Ceph. d. Hierlatz b. Hallstadt," gives three species of 

 small size, Cal. (ArietUes) sp. indei. aff. Nodotianus, D'Orb., Plate III. Fig. 16 ; C'l. 

 (Ariet.) doricus, Plate III. Fig. 3; and Gal. {Arid.) raricostaius. 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 Cal. (Ariet.) Corrcgoiteme. Fig. 

 12-15, which seems to be the young of a stout variety of Juhiistoni ; Cal. (Ariet.) 

 rdroversicostatus, which may be 3'oung of Cal. saUnarium described by Wahner from 

 the Northeastern Alps; Cal. (jEgoc.) heUcoideum, Plate V. Fig. 7, tortuosus, Fig. 8, 

 and carusense, Fig. 10, all belonging apparently to the same species, most likely 

 young or dwarfs of the last named ; 4 and Cal. (Ariet.) raricostatum, Fig. 9, is 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. pi. xxv. fig. 2, 3. 



2 The species accompanying this one. figured on the same plate as Tropites ullratriaskus, Arielites Cam- 

 pigliensis, ligusticus, and 'User, ins. are all apparently true Tropites with tuberculated and coronate whorls in 

 the earlier nealogic stage, and acquiring a keel and pilse 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 



Jokeyli, as given by Hauer, Ceph. d. Halst. Schich., Denks. Akad. Wien. IX.. 1855, pi. iv. 

 8 Dnterst. Lias, Abhandl. geol. Reichsans., VII. pi. iv. fig l'-I. 

 4 Referred by Canavari to the young of proaries in Mem. della Carta Geol. d' Italia. 



