=F 
(Sw) 
Or 
DEVONIAN FAUNAS. 
growth. In the pedicle valve the dental lamella are united to form a 
spondylium, which is supported by a median septum, and in the in- 
ternal casts these dental lamellae and the median septum are repre- 
sented by slits. 
The dimensions of the best specimen observed, apparently a brachial 
valve, are: length, 40 mm.; width, 25 mm.; convexity, 7 mm. 
Remarks.—This species has been recognized at both the Newfound- 
land and the Greenwood lake localities, always in the condition of 
imperfect internal casts, upon which the characters are always more 
or less obscure. There seems to be no other species, however, than 
Amphigenia elongata with which the specimens can be identified. 
SPIRIFER MACROTHYRIS Hall. 
Plate LII., Figs. 1-3. 
1867. Spirifer macrothyris Hall, Pal. N. Y., vol. IV., p. 202, pl. 30, 
figs. 16-20. 
Description.—Shell large, subelliptical in outline, much wider 
than long; hinge-line nearly equaling the greatest width; cardinal 
extremities angular or a little rounded. Pedicle valve moderately 
convex, with a well-defined, rather shallow, rounded, smooth mesial 
sinus; cardinal area of moderate width, a little concave, sharply de- 
fined and extending to the cardinal extremities; delthyrium large, 
broadly triangular. In the internal casts the muscular impression is 
large and prominent. Brachial valve more convex than the pedicle; 
mesial fold prominent, subangular posteriorly and rounded toward 
the front. Surface of each valve marked by from six to ten rather 
broad, depressed, rounded, simple plications on each side of the fold 
and sinus. 
The dimensions of the largest specimen observed from New Jersey 
are: width, 98 mm.; estimated length of shell, 40 mm. 
Remarks.—The only specimens of this species which have been ob- 
served are very imperfect, but they seem to possess characters which 
belong to no other Spirifer than S. macrothyris. Some of the smalier 
individuals from Newfoundland were at first thought to represent the 
Oriskany species, S. murchisoni, but the pedicle valves are less strongly 
