174 PERMIAN FOSSILS. 
though it might, with equal propriety, have been doubtingly referred to the present 
species, it follows that I am quite disposed to extend its range to the Permian region 
of Germany. 
Byssoarca Kineiana, De Verneul. Plate XV, figs. 10, 11, 12. 
Arca Kinerana, De Verneuil. Bull. Soc. Géol. de France, 2™° série, vol. i, p. 32, 1844. 
— — 3 Geol. Russ., vol. i, p. 224; vol.ii, p. 313, pl. xix, fig. 11, 
1845. 
Byssoarca KINGIANA ,, King, Catalogue, p. 11, 1848. 
ARCA — 5 Howse, Trans. T. N. F. C., vol. i, p. 247, 1848. 
— — is Geinitz, Versteinerungen, p. 9, pl. iv, fig. 8 a, 6, c, 1848. 
Diagnosis. —“ Shell inequilateral, oval, transverse, twice as wide as it is long, and 
truncated obliquely at its posterior extremity. Uméones projecting, situated near the 
anterior extremity, which is round. Cardinal margin straight, terminated posteriorly 
by an obtuse angle; with a narrow, triangular, depressed area between the back and 
the cardinal margin. The valves apparently smooth externally.”! (De Verneuil.) 
Byssoarca Kingiana, for the name of which I feel highly complimented by M. de 
Verneuil, who first described it, is very distinct from the foregoing species, although, 
in one respect, not to the extent implied by the original diagnosis; since the valves, 
instead of being smooth externally, as suspected by De Verneuil, are marked with 
rather distant, slightly raised, occasionally dichotomous lines diverging from the 
umbones: these lines might be considered as an incipient form of the ribs charac- 
teristic of Byssoarca striata and &. tumida. It cannot, however, be confounded with 
either species ; as its areas are much narrower, being, in fact, only slightly developed ; 
its umbones more obtuse; its dorsal slopes less impressed; and its byssal sinuses 
smaller. Besides, it does not appear to attain so large a size: my largest specimen is 
an inch in width, and half an inch in length. 
This species is much scarcer than its associated congeners; but it is more widely 
diffused. I have found it only, and very seldom, at Tunstall Hill, in Shell-limestone. 
Dr. Geinitz notices the single German locality,—K6nitz, in Zechsteim-dolomite. M. de 
Verneuil discovered it in the Iitchegulova limestones, forming the base of the Permian 
system, in the valley of the Dioma, government of Orenburg, Russia; and Count 
Keyserling records its occurrence on the Wymm, in Petschora-land. 
Family Nucuuipe, King. 
The members of this group have hitherto been placed in Arcede; but both their 
shell and mollusk possess characters clearly diagnostic of a distinct family. <Arcide 
and Vuculide appear, in short, to be only approximately allied: it must not be over- 
! Geology of Russia, vol. ii, p. 313. 
