BRACHIOPODA. 
203 
I860. Mhynchonella,’D a.vwso's. British Carbon. Brachiopoda, pj). 93-105, pi. xx, figs. 1-13; pi. xxi, 
figs. 1-20 ; pi. xxii, figs. 1-15 ; pi. xxiii, figs. 1-22. 
1860. RJiynclwneUa, McChesnby. Ti'ans. Chicago Acad. Sci , vol. i, jip. 49, 50. 
1862. Rhynchonella, White. Proc. Boston Soc. Nat. Hist., vol. ix, p. 23. 
1865. Rhynchonella, Davidson. British Devon. Brachiopoda, pj). 62, 63, pi. xii, figs. 12-14 ; pi. xiii, 
figs. 6-13. 
1866. Rhynchonella, Meek. Geological Survey Illinois, vol. ii, p. 153, pi. xiv, figs. 4a, h. 
1868. Rhynchonella, Meek. Geological Survey Illinois, vol. iii, p. 450, pi. xiv, figs. la-d. 
1871. Terehratula, Qdenstedt. Petrefactenk. Deutschlands; Brachiopoden, p. 190, j)l. xlii, figs. 5-7. 
1883. Rhynchonella, Williams. American Journal of Science, vol. xxv, ji. 91. 
1884. Rhynchonella, Walcott. Monogi*. U. S. Geol. Surv., vol. viii, p. 155, pi. xiv, figs. 7, 7a. 
1885. Rhynchonella, Clarke. Bull. U. S. Geol. Surv., No. 16, p. —. 
1887. Rhynchonella, de Koninck. Faune du Calcaire Carbonifere de la Belgique, jit. 6, Brachiopodes, 
pis. ix, X, xi, xii. 
Diagnosis. Shells with deep fold and sinus; elevated, and often acuminate 
on the anterior margin; more or less sharply plicated, the plications usually 
being simple, those of the fold and sinus the strongest, and those of the lateral 
slopes often obscure or obsolete. Pedicle-valve shallow; brachial valve deep. 
Teeth supported by vertical lamellse; hinge-plate similar in structure to that 
of Hypothyris ; the median septum of the brachial valve is extremely faint 
when present, but is usually undeveloped. Muscular impressions not large but 
well-defined and clearly subdivided. Vascular sinuses sometimes retained on 
the pedicle-valve, always obscure on the brachial valve. 
Type, Conchyliolithus anomites acuminatus, Martin. Carboniferous limestone. 
It is apparent that these shells, in the character of their internal apophyses, 
are not widely removed from those of the type of Rhynchonella cuboides. The 
contour of the shells affords a difference of fundamental significance, and its 
trihedral expression in R. acuminata is the nearest approach, among palseozoic 
species, to the form of the typical Rhynchonella, R. loxia. 
The group requires a distinctive name, and the term Pugnax has been selected 
as it serves to commemorate von Buch’s term Pugnacecc, which was applied to 
a division of the Rhynchonellas,- embracing the typical forms of this sub-genus. 
This combination of characters appeared in the middle or later Devonian and 
during the various faunas of the Carboniferous became prolific in species. 
Among its representatives in American rocks are R. pugnus, Martin, and R. 
reniformis, Sowerby, of the Chemung faunas of New York; R. alia, Calvin, from 
