633 
PEATE! OX, 
Figs. 1-14. Coloceras (Naut.) globatum (sp. De Koninck), Hyatt; Loc., Visé, 
Belgium, Carboniferous ; Coll. De Koninck, Mus. Comp. Zodlogy. 
Fig. 1. Side view of nepionic and neanic volution, natural size. Fig. 2, same 
enlarged in front view and ends of volutions restored; compare neanic volution 
with the gerontic volution of Vestinautilus pinguts, Pl. ix, Fig. 17; it will be 
seen that this genus resembles the latter in the lateral fluted faces, but has rounded 
sides, such as have been described as appearing in the paragerontic substage of 
that species ; Fig. 2 also shows the impressed zone well-developed in the parane- 
pionic substage. Figs 3-6, sections of meta- and paranepionic substage of Fig. 
to, showing development of outline and correlation of impressed zone with 
nephritic form. The ananeanic substage begins immediately after this on the 
latter half of the still uncoiled first volution and then the longitudinal ridges dis- 
appear on the abdomen and also the crease or hollow central ventral zone, the 
section becomes in the metaneanic similar to that of the upper volution in Fig. 2. 
Fig. 7, enlarged oblique view of apex of same, showing the ana- and metanepionic 
substages and the beginning of the impressed zone in a shaded crescent near the 
base of the figure. Fig. 8, view of venter of another specimen ananepionic and 
a part of metanepionic showing the beginning of the hyponomic sinus in the 
bands of growth. Fig. 9, end view of same with cicatrix. Figs. 10-12, views of 
another specimen showing the first three sutures, impressed zone and ventral 
hollow zone of the paranepionic substage. Fig. 13, shows the impressed zone 
of the ananeanic substage and the beginning of the true impressed zone after con- 
tact inthe shaded crescent-like depression from which the apex has been removed. 
Fig. 14, another specimen of same age with the pseudo-impressed zone and the 
apex (ananepionic substage) in place. In all sections the venter is the lower side. 
Figs. 15-22. Potoceras dubium. Fig. 15, side view slightly enlarged showing 
shape of umbilical perforation and abrupt bending of the paranepionic substage 
when the zone begins. Fig. 16, front view of ana-, meta- and paranepionic sub- 
stages and neanic volution in part. Figs. 17 and 18, enlarged views of same 
without the neanic volution. Fig. 19, enlarged view of details of bands of growth 
and longitudinal ridges taken from same. Figs. 20 and 21, views of ephebic vol- 
ution, natural size. The history of the impressed zone is parallel with that 
of Coloceras except that it comes in only after the abrupt bending of the first 
whorl, and the form and character of the ana- and metanepionic substages 
differ. Fig. 22, view of the ananepionic substage showing the flattened aspect of 
apex. Figs. 22 and 9g (the latter described above) are, however, more distinct 
than the specimens. 
Figs. 23-26. Ephippioceras (Naut.) ferratum (sp. Owen), Hyatt; Loc., Ed- 
mondson Co., Ky., Carboniferous; Mus. Comp Zoélogy. Enlarged four diameters, 
Fig. 23, side of fragment of paranepionic substage, showing also umbilical per- 
foration, apex restored and fragment of cast of ananeanic substage with parts of 
two sutures. Fig. 26, venter of same. The longitudinal ridges are wider apart 
and broader at their crests on the sides than on the central parts of the venter as 
shown in Fig. 23. Figs. 24 and 25 show sections of both ends of the fragment 
covered by shell in Fig. 23. 
PROC. AMER. PHILOS. SOC. xxxII, 143.4 B. PRINTED AUGUST 6, 1894. 
