848 THE PALEONTOLOGY OF MINNESOTA. 
[Protowarthiide. 
This is the oldest known representative of the suborder, but as all the essential 
bellerophontid characters are already well developed in it, we should look for, and 
may confidently expect to find, less advanced forms in the Middle and Lower 
Cambrian rocks. 
The general expression of O. antiquata is such that we can scarcely doubt 
that it is of the type from which the Bucaniide sprang. The modifications required 
to reach the latter stage,—the formation of an apertural slit with its resulting 
dorsal band, and a not very great change in surface markings,—are quite in accord- 
ance with the developmental tendency prevailing in early Paleozoic times not only 
among the Bellerophontacea but among the Kotomacea as well. Further, we are 
satisfied that Owenella is the stock in which the roots of all the other types of the 
group, excepting the Cyrtolitide, are centered. Abundant evidence supporting 
this view occurs here and there through the following pages. 
ProtowarrTuia, n. gen. Aperture large but not abruptly expanded, the outer 
lip bilobate, with a broad and more or less deep sinus but neither a slit nor band; 
dorsum convex, never carinate; umbilicus closed; surface markings very fine, gener- 
ally consisting of more or less obscure crowded lines of growth and delicate 
revolving striz. The inner lip forms a thin granulose deposit over the dorsum of 
the inner end of the last whorl and extends on each side around the umbilical 
region. This portion is covered with interrupted or inosculating lines. Type, 
Bellerophon cancellatus Hall. 
P. cassinensis Whitfield sp. Calciferous. P. planodorsata Ulrich. Utica group. 
P. rectangularis U. & S. Stones River group. P. subcompressa Ulrich. Richmond group. 
P. pervoluta U. &S. Black Riv.and Trenton groups. P. concinna U. & S. ‘f un 
P. obesa Ulrich. Trenton group. P. morrowensis Miller sp. & ae 
P. cancellata Hall sp. Trenton and Cincinnati periods. LP. bilobatus Sowerby sp. Low. Silur. (Probably 
P. granistriata Ulrich. Utica group. not American.) 
P. 2acutilira Hallsp. Hamilton group. 
Bucanetia, Meek.* (Not Koken.}) Back of shell distinctly trilobate, volutions 
enlarging rapidly, compressed dorso-ventrally, scarcely embracing; umbilicus large; 
aperture transverse, the outer lip sinuate; surface markings obscure, delicate, con- 
sisting apparently of both revolving and growth lines. According to Meek there is 
noslit-band. Type, B. nana Meek. The European Upper Silurian fossil, Bellerophon 
trilobatus Murchison, and our common Clinton Bucania trilobata Conrad, probably 
belong here. 
Unfortunately we have not been able to secure a testiferous example of any 
of the three species referred to this genus.{ Admitting the correctness of Meek’s 
* Proc. Amer. Philos. Soc., vol. xi, p. 426; 1870. 
+N. Jahrbuch f. Mineralogie, etc., Beilage Band vi, p. 389; 1889. 
+Since this page was in type we have, through the kindnessof Prof. E. W. Olaypole and Mr. Aug. F. Foerste, been 
enabled to see specimens of B. trilobata Conrad sp.which retained some of the shell. This we find to be comparatively thick, 
and marked externally with very fine revolving lines. The lines of, growth are very faint and they form a broad sinus on 
he central lobe of the back about as in Protowarthia, There is no slit-b@nd. 
