250 
PALEONTOLOGY OF NEW YORK. 
1880. Stricklandinia, White. Proc. U. S. National Museum, p. 48. 
1882. Stricklandinia, Whitfield. Geology of Wisconsin, vol. iv, p. 315, pi. xxiii, figs. 3-5. 
1883. Stricklandinia, Davidson. British Silurian Brachioxioda, Suxipl., pp. 164, 165, pi. ix, figs. 1-5. 
1884. Stricklandinia, Kiesow. Ueber Silur. und Devon. Geschiebe Westpreussens, p. 51, pi. iii, fig. 7. 
1889. Stricklandinia, Nettelroth. Kentucky Fossil Shells, pp. 64, 65, pi. xxxiv, figs. 31-34. 
1889. Stricklandinia, Foerste. Proc. Boston Soc. Nat. Hist., vol. xxiv, p. 321, pi. v, figs. 1-4. 
1890. Stricklandinia, Gagbl. Brachiop. der^Camb. und Silur. Geschiebe im Diluv. der Provinz. Ost- 
und Westpreussen, x^P- 61, 62, xd. iv, figs. 9, 10. 
“ Generic Characters. Shell usually large, elongate-oval, transversely-oval 
or circular; in some species with a straight hinge-line, more or less extended; 
valves nearly equal, varying from depressed convex to strongly convex; a 
short mesial septum in the interior of the ventral valve, supporting a small, 
triangular chamber beneath the beak, as in Pentamerus; in the dorsal valve two 
very short or rudimentary socket plates, which in some species bear prolonged 
calcified processes for the support of the serrated arms. Both valves with an 
area, that of the ventral valve the largest, the dorsal area sometimes incurved 
over the ventral, and concealing it wholly or in part. 
“No muscular impressions have as yet been clearly observed in the ventral 
valve, but in the dorsal there are two oblong or subovate scars a little below 
the beak, one on each side of the median line. * * * surface 
is usually coarsely and rather irregularly covered with radiating ridges, some¬ 
times nearly smooth.” (Billings, Palaeozoic Fossils, vol. ii, pt. i, p. 78, 1874.) 
Type, Stricklandinia Gaspensis, Billings. Middle Silurian. 
These pentameroids are principally remarkable for the unusual development 
of the cardinal areas of both valves in the larger and more typical species, and 
the straight orthoid hinge in the earlier and smaller members of the group. 
The combination of such features with an internal chambered structure is not 
of frequent occurrence among these genera. In Pentamerella and Gypidula 
the definition of the cardinal area of the larger valve is generally obscure and 
its delimitation in these species may be regarded as occasional or spasmodic. 
In Stricklandinia* this feature is sharply defined on both valves, and so 
persistent is it that we look for the origin of this combination, not among the 
various pentameroids which have just passed in review, but to the small, 
transverse shells of the early faunas to which the term Syntrophia has been 
* The name originally used by Mr. Billings for these shells was Stricklandia, but this he withdrew, as 
the term had been used for a genus of fossil plants, and xR'Oxiosed in its place the term Stricklandinia. 
