130 GENESIS OF THE ARIETIDiE. 



have probably come from the " gelbesandstein " of the Trias, near Tubingen, 

 belongs to this species, and it contains also other discoidal varieties, as well as the 

 extraordinary compressed but still discoidal form of striatissimus, Quenst. 



Schlotheimia colubrata, Hyatt. 



Amm. cohibratus, Ziet., Verst. Wiirt., pi. iii. fig. 1. 



Amin. Moreanus, D'Orb., Terr. Jurass. Ceph., pi. xciii. 



Amm. Moreanus, Hatjer, Ceph. Nordostl. Alpen, pi. xv. fig. 1, 2 (not fig. 3, 4). 



JEgoc. Moreanus, Wiught, Lias Amm., p. 322, pi. xvii. fig. 1, 2. 



Amm. angulatus Thalassicus, Quenst., Amm. Schwab. Jura, pi. ii. fig. 4, 5 (not fig. 9). 



Localities. — Deyrolay, Hanover. 



In the Semur collection there is a specimen named Moreanus from the lower 

 part of the same zone with Liastcus, and it may be said to agree with D'Orbigny's 

 figure. 1 This is a variety identical with cohibratus, Ziet., growing to a larger size 

 than catenata. At the diameter of 168 mm. in this specimen, the pilse crossed the 

 abdomen, showing that old age had set in. That this is sometimes a nealogic 

 feature retained throughout life is shown by another specimen, which at the diam- 

 eter of 21 mm. has the pilse continued across the abdomen. 



Schlottieimia angulata, Zittel. 



Summ. PI. XI. Fig. 4. 



Amm. angulatus, Schlot., Die Petrefactenkunde, p. 70. 



Amm. angulatus depressus, Quenst., Amm. Schwab. Jura, pi. ii. fig. 1, pi. iii. fig. 9. 

 Amm. angulatus costatus, Quenst., Ibid., pi. ii. fig. 8. 

 JEgoc. angulatus, Wright, Lias Amm., pi. xiv. fig. 5, 6. 

 Schlot. angulata, Zittel, Handb d. Paleont., I. p. 456, fig. 637. 



Schlot. angulata, Wahner, Unter, Lias, Mojsis. et Neum., Beitr., IV., 1886, p. 163, pi. xix. fig. 1-3, pi. xx. 

 fig. 1-6. 



Localities. — Muhlhausen, Hildesheim, Lyme Regis. 



The young appear to be smooth for about one and a half whorls, then lateral 

 tubercles appear. These spread upon the sides into folds, which on the early 

 part of the fourth or last of the third whorl rapidly become true depressed pilas, 

 and then begin to be continued across the abdomen with a very decided forward 

 bend at the geniculge, and form an acute angle on the abdomen. The depression 

 which obliterates the angle of intersection of the pilae on the abdomen and forms 

 the smooth zone begins on the last half of the fourth whorl. 



On the early part of the fourth whorl the abdominal lobe is somewhat deeper 

 than the superior laterals, and these again very much deeper than the inferior 

 laterals. The saddles are broad and shallow, the superior laterals being a trifle 

 shallower than the inferior laterals. On the first quarter of the fifth volution 

 the bases of the superior and inferior lateral saddles and the tops of the supe- 

 rior lateral lobes have become trifid, or unequally divided, whilst those of the 

 inferior lateral lobes and auxiliary saddles are equally divided. The abdom- 

 inal lobes are shorter than the superior laterals, though the saddles maintain 



1 The original at the Jardin des Plantes is a fragment, and D'Orbigny's figure is in large part a resto- 

 ration, especially with regard to the internal whorls. 



