A New Brach copoda.— Winchell and Schuchert. 291 
about mid-length. A shallow, or sometimes well pronounced 
broad sinus is present, having its origin in the upper third of the 
valve. Area narrow, perpendicular or slightly inclined forward. 
Differs from O. iphigenia Billings, in having the fold and sinus 
reversed, and less number of strive. 
Plate xxxul, figs. 51-58. 
Formation and locality. Not rare in the upper portion of the Hudson 
River group at Spring Valley. 
Zygospira uphami. 
This species occurs in the Galena limestone about 50 feet above 
the layers holding Z. recurrirostris in abundance. Its general 
expression shows it to be a descendant from Z. recurvirostr’s but 
differing from it in its much larger size, stronger convexity of 
_the valves and somewhat finer striz. The last feature is more 
apparent than real, due to the greater size of Z. uwphami. Some 
specimens from which the shell has partially been exfoliated, 
show the interior of the pedicle (ventral) valve to have a_ strong 
muscular cavity extending from the beak to about one third of 
the length of the shell. From the antero-lateral margins of the 
area originate two prominent, diverging ridges, probably the 
markings of the main trunks of the vascular system, which become 
obsolete near the front margin. The crural plates of the brachial 
valve are very strong, and at their bases coalesce with a stout but 
rather short median septum, upon each side of which posteriorly 
are situated two depressions of the adductor scars; the second 
pair undefined. 
Z. uphami is the linking species between Z. recurvirostris 
and Z. erratica Hall, and Z. headi Billings. Its nearest relations 
are with Z. erratica. 
Plate xxx1V, figs. 45-48. 
Formation and locality. Middle of the Galena horizon at Weisbach’s 
dam, near Spring Valley, and near Wykoff and Fountain. 
Hallina, n. gen. 
Shells small, articulate, rostrate, biconvex, semi-plicate. Ped- 
icle opening bounded laterally by incomplete deltidial plates. 
Calcified brachial supports comparatively long, somewhat longer 
than one-half the length of the brachial valve, and in form much 
as in Waldheimia. The detailed structure of the articulating and 
