PLATE LXIII—Continued. 
Genus ANASTROPHIA, Hall. 
Page ‘224. 
Anastrophia deflexa, So\verl)_y. 
Fig. 28. Profile of a normal adult example ; showing- the surface plication and the predominant convexity 
of the brachial valve. 
Wenlock limestone. Wenlock Edge, England. 
Fig. 29. Cardinal view of a specimen which has been transversely sectioned in the umbonal region ; show¬ 
ing the supported spondylium of the pedicle (lower) valve, and the septal plates of the brafdiial 
valve, bearing the crural apox^hyses. 
Wenlock limestone. Island of Gotland. 
Anastrophia internasoens, Hall. 
Fig. 30. Cardinal view of an internal cast, representeil with the brachial valve above ; showing the cavi¬ 
ties of the seiital and socket x'lates in the brachial valve, and of the spondylium and its 
median septum in the pedicle-valve. X 2. 
Niagara dolomites. Near Milwaukee, Wiseomin. 
Anastrophia Verneuili, Hall. 
Figs. 31, 32. Ventral and cardinal views of a large individual; showing the contour and character of the 
surface plication. 
Figs. 33, 34. Dorsal and front views of a somewhat smaller specimen with more regularly and sharply 
plicated surface. 
Fig. 35. An enlargement of the interior of the umbonal region of conjoined valves, the pedicle-valve being 
represented below. In the brachial valve the convergent septal jilates bear lateral lulobetl 
expansions or flanges, which are the crural apophyses as shown in section, in figure 29. In the 
pedicle-valve the walls of the supytorted spondylium are folded over each other in such a man¬ 
ner as to form a tubular chamber. This ay^xiears to be an abnormal chai’actei-, as it has been 
observed in this instance only, but it is nevertheless a natural growth without evidence of 
break or lesion in the walls of the sy^ondylium. X 2. 
Fig. 3(j. Similar- yjarts in another specimen in which the spondylium is normally oyien, but the crural 
apophyses less yierfectly retained than in the shell represented in fig. 35. X 2. 
Lower Helderberg grouji. The Helderhergs, New York. 
Fig. 37. The interior of a yiortion of the brachial valve ; showing the cavity of the sessile syionilyliura or 
septal plates and the four scars of the adductor muscles. 
Lower Helderberg group. Perry county, Tennessee. 
Fig. 38. A similar interior with the sejital yilates and muscular scars more sharyily derined ; showing also 
the false foramen produced by the encroachment of the septal cavity or sjiondylium uy:(on the 
beak. 
, Lowei- Helderberg grouy^. The Helderhergs, Neto York. 
Genus PORAAIBONITES, Pander. 
Page ‘2‘25. 
PORAMBONITES yEQUIROSTRIS, SclllotlieilU. 
Fig. 39. Cardinal view of a specimen showing the cardinal area on each valve and, by translucence, the 
double sep)ta of both valves. X 2. 
Fig. 40. A x)ortion of the interior of the x>edicle-valve; showing cardinal area, delthyrium and teeth. 
Fig. 41. A similar view of the brachial valve; showing cardinal area, delthyrial opening and dental 
sockets. 
Figs. 42, 43. Profile and front views of .a ventricose shell; showing the relative convexity of the valves and 
the development of median fold and sinus. 
Lower Silurian. Russia'. 
PORAMBONITES GIGAS, Sclllllidt. 
Fig. 44. Cardinal view of an average specimen; showing the cardinal area and apical foramen on each 
valve. By the exfoliation of the shell of the brachial (upper) valve, the bases of the diverg¬ 
ent septal plates are exposed. 
Lower Silurian (Lykhohner-Schichten). Estland, Russia. 
