20 G. LINDSTRÖM, THE ASCOCERATIDAE AND THE LITUITIDAZ. 
without sutures. The annulation of the shell is not at all characteristic to Aphragmites 
as one species only has annulations, the other not. HyraATtTt says that the septa are in the 
living chamber». But what preeminently characterizes a body chamber is the absence 
of septa. If there are septa formed on the bottom af a body chamber as often is the 
case, the boundaries of that chamber are altered and removed, but it cannot be said that 
the septa are in the body chamber, being in reality beneath it. As to Ascoceras it may 
seem justifiable to compare the inflated shell formed on a long series of septa and as 
long as itself rests without septa (as in the Aphragmites stage), with the swollen body cham- 
ber of Gomphoceras, but there is the great difference, that septa have been formed on its 
bottom in Ascoceras and sometimes two different sets, and when this occurs the volume 
of the body chamber has been restricted. HvaArTt also says that Glossoceras »clearly» 
is derived from an annulated stock like Cyrtoceras residuum BARR., which has »similar» 
annulated whorls. It is very difficult to see how this can be, as the known forms of 
Glossoceras are not annulated at all, but have very smooth and finely striated shells. 
ZirTEL in his »Handbuch der Palontologie Bd. 1, p. 371 adopts partly the same 
views as HyaTtTt. In figure c. ZITTEL has rightly designated the septa (or »Luftkammern>) 
to the left of the siphuncle as continuations of those on the right or the sigmoid air-cham- 
bers. But this is lost view of in the descriptive letterpress, where, if I cateh the meaning 
right, he speaks of two sets of air chambers or septa. »Bei gönstiger Erhaltung beobach- 
tet man auf der dorsalen (?) Seite der Schale hinter den Wohnkammern einige niedrige 
Kammer», with a normal siphuncele. I suppose he means the same as those signed c in 
the figure e. He seems also to adopt two different kinds of siphuncele on the dorsal side. 
He supposes that Aphragmites represents a stage where some normal, low air chambers 
have been truncated from the lower end, but quite the same might be as well said of 
Ascoceras. The latest description given is by Foorp in Cat. Foss. Cephalop. of Brit. Mu- 
seum p. 246, which is very complete and lucid. As he had no specimens to show him 
the interior of the sigmoid portion of the septa he in fig. 42 interpreted ec. s. as coale- 
sced septa, which in reality is only the first sigmoid, the others being developed only on 
the sides, which are cut away. In figure 41b., copied from BARRANDE, there ought to 
be seen, on the ventral side, lower down, the sutures of the septa. 
1. Ascoceras cochleatum n. 
Plate I fig:s 1—1 a, 7—10, pl. VI.:;f. 1 a—c. 
Distribution. Six specimens have been found in the soft, grey shale near Wisby, in 
the stratum signed b and homotaxical with Upper Llandovery. 
Only the Ascoceras stage of growth is at present known. 
Shell short, obese, ovate, a little tapering: towards both ends with a necklike con- 
striction somewhat below the aperture. 'The transverse section is ovate. About ten trans- 
verse ribs cover the outside and three or five very narrow ones cross the neck. The 
larger ribs are much distantiated, with an interstice of one millimetre, faintly scooped 
out. As they are preserved only as nuclei without shell, any finer ornamentation cannot 
be discerned. The ribs are nearly parallel with each other and at right angles with the 
axis of the shell; they are arched downwards both on the dorsal and ventral side; rather 
