﻿4C8 



Lit. teres, Holm {Pal. Abh., Dames et Kayser, iii, hft. i, PL v, 

 Fig. 5-8). 

 Loc, Kandel, Esthland. 



The smooth whorl has in section an abdomen somewhat broader 

 than the dorsum as figured by Dewitz and the siphuncle closer to 

 the dorsum than in Odini. The living chamber is free and the 

 aperture like that of angulatum. The impressed zone is continued 

 to the edge of the aperture. It suffers, however, a certain obvious 

 diminution and the dorsal edge of the aperture is merely flattened 

 instead of being concave as is the dorsum at the beginning of the 

 living chamber. This peculiarity is described by Schroder, who 

 gives the best figures. 



Holms' figures of the young have been copied in outline on 

 PL vi, Fig. 21-27. These sections show how closely the young 

 resemble those of Schroederoceras Eafotti, a.nd if correctly identified 

 and drawn indicate considerable variation in the form of the 

 young and the relations of the umbilical perforation. In Fig. 

 21, it is between the ananepionic and paranepionic ; in Fig. 22, it is 

 situated as in Trocholites, viz., carried more on to the metanepionic 

 substage, and is differently shaped. 



The young (Figs. 23-27) give a rare opportunity for the study of 

 the nepionicstage. The ananepionic substage (Figs. 26-2 7) is like that 

 of Eatoni, and one sees the peculiar shape of the apex and the great 

 comparative depth of the apical chamber. The first septum and 

 caecum of course belongs to the later metanepionic substage, but 

 the whorl itself is ananepionic, and this a broad elliptical section as 

 seen in the front view of Fig. 26. The dorsum broader than the 

 venter and rounded. The shape is here decidedly cyrtoceran. 

 The first septum and caecum is seen in this view and the siphuncle 

 is subventran. In the metanepionic it changes as in other forms 

 towards the centre. This is shown by its becoming extracentroven- 

 tran in the third septum, which belongs to the later age of the para- 

 nepionic substage. At the angle of the turn a faint, but plainly 

 marked dorsal furrow appears. The point at which this im- 

 pression occurs is like that of similar forms of early faunas, and 

 the shape of the whorls show a very rapid increase of the lateral 

 diameters and the usual approximation to the kidney- shaped whorl 

 which characterizes rapidly growing shells of Nautiloids at similar 

 substages. It seems probable, therefore, that this may have been 



