170 THE PALEONTOLOGY OF MINNESOTA. 
[Escharopora. 
In 1886 I believed this species to be a close relative and, perhaps, the western 
representative of Hall’s EH. recta. Since making my final investigations, with aug- 
mented material in all stages of. growth, much of it in an excellent state of preser- 
vation, I find that the relationship is more remote than it seemed at first. Although 
Ihave not had an opportunity of examining authentic examples of LH. recta, Hall’s 
original figures are sufficiently diagnostic to warrant us in saying that the New 
York species has zocecial apertures agreeing both in shape and arrangement with 
those of E. falciformis (Nicholson) and the closely related E. acuminata (James). 
The last is the form referred to (loc. cit.) as occurring “in the lower beds of the 
Cincinnati group (Utica shale ?) in Ohio.” The form mentioned at the same time as 
found in Tennessee (“Glade” limestone) greatly resembles E. acuminata, but as I 
have not yet examined its interior structure, I cannot say that it is really the same. 
Whatever it may turn out to be I am satisfied that it is distinct from H. subrecta. 
Comparing ordinary examples of the Minnesota species with any of these forms, 
indeed with all of the known simple species of the genus, we find that in none 
of the latter, save for a short distance above the pointed base, are the zocecial 
apertures confluent longitudinally, 7. e. connected by narrow channels, as is the case 
in E. subrecta. Nor do any of them exhibit as much difference in the size of the 
marginal and central rows of apertures. Of unbranched species, EF. subrecta is also 
the only one known to me in which the primitive ¢ell assumes the peculiar clavi- 
form shape shown in figs. 25 and 26. In most of the other species, perhaps all save 
E. angularis, the hemisepta are more pronounced. These two features alone are 
sufficient in distinguishing thin sections of H. subrecta. Compared with the branch- 
ing forms, we find one, and it is associated in the same beds, that agrees in many 
respects. This is the next described L. confluens, having confluent zocecial apertures, 
a similar difference in the size of the marginal and central rows, and an internal 
structure nearer that of KH. subrecta than any other species. But the zocecial 
apertures are wider, a fact noticeable enough to enable one to distinguish the 
merest fragments. There is, of course, no likelihood of confusion when complete 
zoaria are available. > 
Formation and locality.—Common in the middle third of the Trenton shales at Minneapolis and 
other localities in the state, and Decorah, Iowa. Perhaps, also, in the lower third of the shales, but rare 
in these and smaller than usual. A single example collected by Mr. Charles Schuchert from the ‘*‘ Lower 
Blue beds” near Beloit, Wisconsin, seems to belong to this species. 
Mus. Reg. Nos. 5929, 7558 and 7597. 
