442 
PALEONTOLOGY OF NEW-YORK. 
llliyiiclioiiella liairandi. 
Plate GUI. Fig. 3-8. 
Khynchonella barrandi : Hall, Regents’ Report for 1856, p. 82; Palaeozoic Fossils, 1857, p.42. 
Shell very large, ovoid or subglobose; full-grown specimens higher than 
wide, vertically flattened on the sides. Dorsal valve very convex, often 
extremely elevated : beak incurved; cardinal border on each side of 
the beak profoundly sinuate. Ventral valve much the smaller, strongly 
arcuate longitudinally, having a broad shallow rounded sinus towards 
the front, abruptly inflected at the lateral margins which are distinctly 
angular, prolonged in front into a broad rounded linguiform projection 
which fills the sinus in the opposite valve. 
Surface marked by thirty to forty simple (rarely bifurcating) strongly 
elevated plications on each valve, as shown in casts of the interior : 
plications rounded or subangular. 
This species has occurred only in casts, which are generally more or less distorted. 
It is the largest of the genus known to me in the rocks of the country. The great 
size, with the strongly marked internal characters which are impressed upon the 
cast, will serve to distinguish this species from any other yet known. 
In many respects it resembles R. speciosa , which may be regarded as a representa¬ 
tive form in the Maryland rocks : it is, however, distinguished from that shell by 
its larger size, its more elevated dorsal valve and relatively broader form, and its 
broad shallow rounded sinus near the front of the ventral valve. 
Fig. 3. Cast of the ventral valve, showing the large muscular impression. The area of the 
adductor muscles is not represented as large as in the specimen. The depression 
in front is less than one-eighth of an inch below the plane of the more prominent 
margins. 
Fig. 4. A similar cast of a smaller individual, in which the form of the rostral cavity is 
better preserved than in the preceding. The casts show a great thickening of the 
shell at the beak. 
Fig. 5. Cardinal view of a specimen which is a cast from the interior of both valves, showing 
the great elevation of the dorsal valve, the strong median septum, and the deep 
sinuosity on each side of the beak. 
Fig. 6. Front view of the same specimen. 
Fig. 7. Lateral view of the same, showing the great lateral extension of the dorsal valve. 
Fi". 8. Profile view of a cast of the ventral valve, showing the abrupt inflection at the 
margin and the expansion of the shell below the beak, which fills the lateral 
sinuosities in the opposite valve. 
Geological position and localities. In the Oriskany sandstone ; Albany and Scho¬ 
harie counties. 
