THIRD, OR VERMICERAN BRANCH. 157 
The sutures have reverted to larval 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 Conybeari. The rate of increase in the 
bulk of the whorl by growth is also less than in Conybeari, 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’ 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 Zodlogy received in exchange from the Museum 
of Stuttgardt a young specimen of this species labelled “ Amma. daqueus, Quenst., 
Lias, and found with Amm. psionotus at Nellingen.”? The genicule 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.* 
A specimen from the Arietenkalk in the Museum of Tiibingen, and belonging 
either to this or to Cad. longidomus, has a rupture in the shell at an early age, and 
is distorted. The distortion of the spiral is slight, but the pile 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 pile. 
The diameter of this specimen is about 39 mm. 
Vermiceras Conybeari, Hyarr. 
Summ. Pl. XI. Fig. 24. 
Amm. Conybeari, Sow., Min. Conch., I. p. 70, pl. cxxxi. 
ve sh D’Ors., Terr. Jurass. Ceph., p. 202, pl. 1. 
te . Quenst., Amm. Schwab. Jura, pl. xv. fig. 1. 
us: + Hauer, Ceph. d. Nordostl. Alpen, p. 16, pl. ii. fig. 1-6. 
Discoc. Conybeari, L. AGAssiz, Bull. Mus. Comp. Zodl., I. No. 5, p. 77. 
Ariet. Conybeari, Wrieut, Lias Amm., pl. ii. fig. 1-3. 
Amm. obliquecostatus, Zimv., Verst. Wiirt., p. 20, pl. xv. fig. 1. 
Amm. Bonnardi, D’Ors., Terr. Jurass. Ceph , p. 196, pl. Ixiv. 
Ariet. Bonnardi, Wricut, Lias Amm., p. 196, pl. xi. fig. 1-3. 
Ariet. Conybeari, Hersion, Széklerland, Mitth. Jahrb. ungar. geol. Anst., V. pt. 2, pl. xx. n. 
Ariet, multicostatus, Herpicn, Széklerland, Ibid., pl. 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 pile on the third whorl. 
1 Amm. Schwab. Jura, pl. xiii. fig. 6. 2 See Plate I. Fig. 17. 
® A similar form is figured by Quenst., Amm. Schwab. Jura, pl. vi. fig. 3, as 4mm. longidomus ceger. 
