630 
PLATE. Valine 
Figs. 1-8.* Remeléceras impressum; no locality: Coll. Mus. Comp. Zodlogy. 
Natural size. Fig. 1, side view showing sutures and annular muscle in base of 
living chamber. Fig. 2, ventral side of fragment of same specimen. Fig. 3, dor- 
sal side of same fragment with impressions of annular muscles on cast. Fig. 4, 
section of end of living chamber showing the decrease of the impressed zone in 
the anagerontic substage. Fig. 5, dorsal view of the second and younger frag- 
ment of same. Fig. 6, section of older end of same showing depth of impressed 
zone in the ephebic stage. Fig. 7, still younger fragment of same, showing the 
dorsal sutures of a late neanic or anephebic substage. Fig. 8, section. 
Figs. 9-13. Hercoceras mirum, Barrande. Figs, 9-12, slightly enlarged, 
Koneprusy. Fig. 13, natural size, Hlubocerpy, Mus. of Comp. Zodlogy, Schary 
Coll. Figs. 9 and Io, side view and front of the ananeanic substage showing first 
beginning of contact furrow and the trochoceran form of the young which is more 
marked than in the adult. Figs. 11 and 12, side view and front of paranepionic 
substage of the same specimen showing the absence of the dorsal furrow just be- 
fore the apex is reached. 
Figs. 14and15. Hercoceras irregularts (sp. Barrande), Hyatt; Loc., Bohemia; 
Mus. Comp. Zoél. Fig. 14, side view of meta- and paranepionic volution, show- 
ing the peculiar coste without longitudinal ridges of this genus. Fig. 15 shows 
the form in section of the meta- and paranepionic whorl and the absence of the 
contact furrow in correlation with the rounded form of whorl. The cecum is not 
correct; this organ is large and ventrocentran in this specimen. 
Figs. 16-20. Anomaloceras anomalum (sp. Barrande), Hyatt; Mus. Comp. 
Zoblogy, Schary Coll. Slightly enlarged. Fig. 16, section passing through umbil- 
ical perforation which is filled with a peculiar dense shell-like deposit, not found 
so far in other forms, and also cutting the meta- and paranepionic substages, The 
neanic stage with a deep impressed zone and the two sections of the outer whorl 
which are in the ephebic stage. The siphuncle appears to be nearer the centre 
in the metanepionic substage in this and in Fig. 17 than in the later stages. 
There is a dorsal furiow at the usual place beginning beyond the gyroceran curve 
in the paranepionic substage in correlation with the nephritic outline of this sub- 
stage. Fig. 17, view of a section of the metanepionic and paranepionic substages 
of same cutting deeper into the umbilical perforation which is becoming nar- 
rower. Fig. 18, a still deeper cut which has passed through the apex of the 
conch and shows the first contact of the whorls. Fig. 19 shows the beginning 
of the contact zone, the paranepionic section having passed into the ananeanic and 
below the rounded ananepionic has replaced the metanepionic volution. Fig. 20,a 
still deeper cut, showing the shell of the ananepionic substage becoming broader 
through the approach of the section to the exterior of the ananepionic apex. A 
shade farther and the ananeanic and metaneanic sections would blend into one 
long figure and the ananepionic would disappear. 
Figs. 21-23. Déscoceras Graftonense (sp. Meek and Worthen), Hyatt; Loc., 
Waukesha, Wis., Niagara Group; Mus. Comp. Zodlogy, Day Coll. Natural size. 
* Fig. 1 has n0 number on the plate. 
