New and Little Known American Paleozoic Ostracoda. 105 
uncertainty respecting the determination of the anterior and pos- 
terior ends, and, in some cases, even of the dorsal and ventral 
edges, it stands to reason that a single good figure is a more potent 
aid in the work of identification than a whole page of description. 
But it requires no mean knowledge of the subject to make cor- 
rect and reliable illustrations of the species, and as the English 
authors mentioned above were much more experienced than those 
American authors who have occasionally described species of 
Ostracoda, the obvious difference in the reliability of their respec- 
tive illustrations is explained. This remark applies to my own 
early work as much as to that of others. 
Two factors, then, may be said to have held the progress of the 
study of the Ostracoda of American rocks in check: the absence of 
interest and experience on the one hand, and a lack of sufficiently 
good and abundant material on the other. In my own case, I 
hope I may say truthfully that the, at least partial, removal of the 
first difficulty, resulted naturally from overcoming the second. 
In my work on the #ryozor, I have had occasion to institute 
washings of shaly and other soft or friable strata, that I might 
obtain the smaller forms in a free condition. In many cases the 
residue contained not only the desired Bryozoa, but numerous 
other small organisms, chief among them the separated valves, and 
often complete carapaces of Ostracoda. The task of picking the 
minute valves out of the material containing them is very labo- 
rious and trying to the eyes, the work having to be done under a 
lens. In each instance, therefore, only a small portion of the 
material was picked over, so as to furnish, as it were, a sample of 
the contents of each. 
I had, besides, the advantage of benefiting from similar wash- 
ings carried on by Prof. J. M. Nickles, Mr. Charles Schuckert 
and Mr. Ernst Vaupel, who very kindly turned small samples of 
their results over tome. Many of these remain as yet unpicked. 
To Mr. Victor Lyon, of Jeffersonville, Ind., I am also indebted 
for a small quantity of fine residue from his extensive washings in the 
noted Devonian Sryozoa bed of the Falls of the Ohio. This proved 
quite rich, and went far to complete my own collections from that 
interesting locality. It is unfortunate, however, that Mr. Lyon 
and others who have made washings there did not save the fine 
sand left after picking out the Avyozoa and other fossils. Thou- 
sands of beautifully preserved Ostracoda were no doubt thrown 
