250 PALEONTOLOGY OF NEW YORK. 



1880. Stricklandinia, White. Pi-oc. U. S. National Museum, p. 48. 



1882. Stricklandbiia, Whitfield. Geology of Wisconsin, vol. iv, p. 315, pi. xxiii, figs. 3-5. 



1883. Stricklandlnia, Davidson. British Silurian Bi-aRhiopoda, Suppl., pp. 164, 166, pi. ix, figs. 1-5. 



1884. Strlcklandinia, Kiesow. Ueber Silur. nnd Devon. Geschiebe Westprenssens, p. 51, pi. iii, fig. 7. 

 1889. Strlcklandinia, Nettelroth. Kentucky Fossil Shells, pp. 64, 65, pi. xxxiv, figs. 31-34. 



1889. Stricklandinia, Foerstb. Proc. Boston Soc. Nat. Hist., vol. xxiv, p. 321, pi. v, figs. 1-4. 



1890. Stricklandinia, Gaoel. Brachiop. derCamb und Silur. Geschiebe Im Diluv. der Provinz. Ost- 



und WestpTttussen, pp. 61, 62, pi 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 Penlamerus ; 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. * * * The 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 Gaspmsis, 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 Gypiddla 

 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 Stkicklandia, but this he withdrew, as 

 the term had been used for a genus of fossil plants, and proposed in its place the tei-m Stricklandinia. 



