485 
rapidly towards the dorsum, attaining a fixed position in the fifth 
septum, if I am right in estimating the first septum drawn by Whit- 
field as the second.* 
It is much larger in the nepionic stages, contracting as it nears 
the sixth, and becoming a narrow tube in the seventh septum. 
Subsequently it again increases by growth as the shell grows larger, 
so that it has the usual large diameter common in this group. IEf 
the trend of the siphuncle towards the apex from the dorsum to 
the centre is followed out it can be seen that the caecum must have 
been situated somewhat on the ventral side in the apical chamber. 
The rapidity with which the siphuncle becomes propiodorsan, 
attaining this position in the metanepionic substage or as the first 
whorl bends to assume the gyroceran curve, shows affinity appar- 
ently for Trocholites, but the position in the second septum and 
the size of the siphuncle and the sutures of later stages are not in 
favor of this view. The form of the whorl is very similar to that 
of Schroederoceras Eichwaldi, but from this it is separated by the 
sutures, which in the ephebic stage on the fourth whorl have slight 
saddles instead of lobes on the venter and the siphuncle is not so 
close to the dorsum and is larger. The suture of the earlier stages 
are straight and are trocholitean in aspect, with well-marked dorsal 
lobes, as is also the form and ornamentation of the young whorls, 
which are slightly costated. 
There is a well-marked contact furrow, and I did not find the 
tendency of the last whorl to become free, as described by Whit- 
field, the contact furrow being well defined at the termination of 
the whorls in the original of Fig. 5, Pl. xxix, of his work. 
The slower growth and distinct form of the apex, which is more 
cylindrical and not cap shaped, and the development of the 
siphuncle, separates it from the young of Schroederoceras Eatoni, 
and also that of Schroederoceras teres and Trochoiitoceras Walcott. 
Although the position of the siphuncle at an early stage is not 
yet known in species of Litoceras, this species is obviously dis- 
tinct because of the narrowness of the whorls, which resemble 
those of #a/oni in outline. Besides the ventral saddles, the sutures 
of the fourth volution have well-marked lateral lobes and dorsal 
lobes in the contact furrow. The whorl remains throughout 
life in transverse section depressed, elliptical, as in Trocholites, 
*I am not satisfied with this correction. The aspect of the first chamber is more nat- 
ural in Whitfield’s drawing than in mine. 
