THIRD, OR VERMICERAN BRANCH. 157 



The sutures have reverted to larv.il outlines. On the eighth whorl the lobes are 

 all of equal length ; the superior lateral saddles, however, are deeper than the 

 inferior laterals, and the first auxiliary saddles not more than half as deep as the 

 inferior laterals. 



The abdominal lobe and the larger saddles are much shallower in proportion 

 to their breadth in this species than in Gonyleari. The rate of increase in the 

 bulk of the whorl by growth is also less than in Gonyleari, and the umbilicus 

 shallower. The longest living chamber was observed in a specimen in the Museum 

 of Stuttgardt from Vaihingen ; it was full one and a half volutions in length, 

 and not complete. Quenstedt 1 figures a senile specimen with a living chamber, 

 the aperture preserved, which is a trifle over one and a half volutions in length. 

 The aperture is remarkable for having no lateral sulcations, and no abdominal 

 rostrum. It would be instructive to compare this with the aperture of an adult 

 or young specimen, since it suggests degeneration in the rostrum, and, if this be 

 true, is another characteristic occurring through senile metamorphosis which is 

 analogous to the younger stages. 



The Museum of Comparative Zoology received in exchange from the Museum 

 of Stuttgardt a young specimen of this species labelled " Amm. laqueas, Quenst., 

 Lias, and found with Amm. psilonotus at Nellingen." 2 The genicular had already 

 begun to be developed, and the presence of a subquadragonal form of whorl, as 

 well as the keel and immature channels, at such an early age, shows that this 

 must have been a vermiceran and not a caloceran species. 3 



A specimen from the Arietenkalk in the Museum of Tubingen, and belonging 

 either to this or to Gal. longidomus, has a rupture in the shell at an early age, and 

 is distorted. The distortion of the spiral is slight, but the pila? cross the abdomen, 

 which has no keel. On the first part of the exposed whorl they are more or less 

 alternate, but subsequently quite regular, and on the latter part of this whorl a 

 keel-like ridge appears below, though not high enough to interrupt the pilae. 

 The diameter of this specimen is about 39 mm. 



Vermiceras Conybeari, Hyatt. 



Summ. PI. XI. Fig. 34. 

 Amm. Conybeari, Sow., Min. Conch., I. p. 70, pi. exxxi. 



" " D'Orb., Terr. Jurass. Ceph., p. 202, pi. 1. 



" " Quenst., Amm. Schwab. Jura, pi. xv. fig. 1. 



" " Hauer, Ceph. d. Nordostl. Alpen, p. 16, pi. ii. fig. 1-6. 



Discoc. Conybeari, L. Agassiz, Bull. Mus. Comp. Zool., I. No. 5, p. 77. 

 Ariet. Conybeari, Wright, Lias Amm., pi. ii. fig. 1-3. 

 Amm. obliquecostaias, Ziet., Verst. Wiirt., p. 20, pi. xv. fig. 1. 

 Amm. Bonnanli, D'Orb., Terr. Jurass. Ceph ,p. 196, pi. lxiv. 

 Ariet. Bonnardi, Wright, Lias Amm., p. 196, pi. xi. fig. 1-3. 



Ariet. Conybeari, Herbich, Szeklerland, Mitth. Jahrb. ungar. geol. Anst., V. pt. 2, pi. xx. b. 

 Ariet. multicostatus, Herbich, Szeklerland, Ibid., pi. xx. A, xx. B. 

 Localities. — Lyme Regis, Semur, Salins, Mohringen, Vaihingen, Balingen, Waltzing in Luxemburg, Adnet. 



The young of this species is smooth throughout the first volution. On the sec- 

 ond whorl scattered folds appear, which develop into true pilse on the third whorl. 



1 Amm. Schwab. Jura, pi. xiii. fig. 6. 2 See Plate I. Fig. 17. 



8 A similar form is figured by Quenst., Amm. Schwab. Jura, pi. vi. fig. 3, as -4mm. longidomus ozger. 



