507 
Notling* shows conclusively that there are two groups usually 
included in Lituites that differ in their lines of growth and aper- 
tures, etc. The true Lituites have, according to Notling, four 
principal sinuses, deep ventral and dorsal and shallow lateral 
sinuses. Schréder has criticised this statement, making out five 
sinuses and five crests in the apertures and lines of growth. N6ét- 
ling’s} statement is substantially the same so far as the larger sinuses 
and crests are concerned, but Schréder pointed out that the dorsal 
sinus was subdivided by a central crest into two smaller sinuses. 
The correct way of describing the sinus of the inner side, judging 
by the growth and development, is to regard it as the dorsal sinus, 
and the dividing crest and minor sinuses being developed later as 
minor or subsidiary dorsal crest and sinuses. 
Holmt has confirmed this view and, with the fine materials at his 
command, has figured the dorsal sinus spreading at the base and 
divided by a slight reéntrant crest, which is also reflected in the 
lines of growth on that side of the living chamber, while the ven- 
tral sinus is deeper and narrower and undivided. ‘These facts 
increase the differences of the aperture between Lituites and Ancis- 
troceras, and at the same time the slight median crest in the aper- 
ture and lines of growth on the dorsum of Lituites makes the 
affinity with €ycloeeras and Ancistroceras clearer than it would’ 
otherwise be. The crest and sinuses are also very much more pro- 
nounced in Lituites, and the enrolled portion of the whorl is con- 
tinued longer and is more 'closely coiled, the whorls being in con- 
tact for between three and four volutions. Holm’s figures of Zz¢. 
Zitwus show that on the early part of the straight whorl the lines of 
growth are entirely different from the later parts of the same whorl. 
The outlines have a slight, shallow dorsal sinus, the median dorsal 
crest not having yet been developed. The same peculiarity is 
observable in Nétling’s figure on a part of the shell preserved and 
show the lines of growth at about the same stage of growth, and 
also upon Lossen’s figure of the same species. ‘There are also 
decisive costations on the coiled whorls, which are similar in both 
of these figures. These in the younger substages are bent apically 
towards the venter and forwards towards the dorsum, and have not 
the more complex curves of the older stage. 
*“ Beitr. z. Kennt. d. Ceph. a. Silurg. d. Prov. Ost-Preussen,”’ Jahrb. d. k. Preuss. Geol. 
Landesanst. u. Bergak., 1883, p. 126 et seq., and Zeitsch. Deutsch. Geol. Gesell., 1882. 
+‘ Untersuch. u. Sil. Ceph.,’’ Pal. Abt., Dames et Keyser, v, heft iv, p. 44. 
{Aftryck. Geol. Foren. Stockholm Forhandl., xiii, 1891. 
