Te Li TEED) OX, 
CoILOPOCERAS, SPHENODISCUS. 
Wrasl—459 Coilopocenasmovimericanumpely alles ae eee eee eee ees 94 
1-3. Natural size, showing hollow keel, etc. 
4. One entire lateral suture and parts of two others, x 2. The terminations 
Figs. 
of the saddles were more or less pointed depressions in the cast and 
were not at first observed. 
Near Carthage, N. Mex.; my collection. 
Mrassip=2iley Colomocenas/ Goulet i alelay cutstie ete epee aes esata a yaar eee bn gee ne aa eee Pe reve 91 
5, 6. Natural size, section partly restored; see also Pl. XI, fig. 1. 
Figs. 
oI 
Lateral suture same as in side view, x 2. 
The dorsal suture of same age, but a suture or two later. 
9 
9. Youngest suture shown in fig. 5, « 2, showing the marked changes that 
occur on this volution. 
10. First to third suture of nepionic stage, >< 20. 
lla. An entire suture of latter part of first volution, >< 20. 
11 
13 
14 
. Two entire sutures of first quarter of second yvolution, X 20. 
. Entire suture of fourth quarter of fourth volution, x 8, when the sutures 
“are beginning to show subdivision. 
. The protoconch and part of the first volution, < 22, same age as fig. 14. 
. More enlarged side view of the same. 
15, 16. An older stage of the same shows less of the protoconch and more 
sutures. 
17, 18. A still older stage, showing the decreasing transverse diameter of the 
yolution in the goniatitic stage, and the first constriction or mark of 
a nepionic aperture. 
19, 20. An older stage of same, center of fig. 6, and also of fig. 1, Pl. XI. 
21. Shows the hyponomic sinus of constriction or permanent aperture given 
in figs. 18 and 19. The normal rate of growth and increase in diameters 
of yolution has begun in this nepionic substage. 
Near Carthage, N. Mex.; my collection. 
Fie. 22. [Suture of Sphenodiscns introduced for comparison.—T. W. 8. ] 
272 
