DR. T. DAVIDSON ON EECENT BRACHIOPODA. 35 



Shell subpeutagoual or ovate, longer than wide, indented in front, fiexuously waved 

 towards the margin. Dorsal valve convex, anterior half biplicated, a median concave 

 depression commencing at about half the length of the valve, separating the two rounded 

 ribs. Ventral valve convex, somewhat flattened along the middle and divided on the 

 anterior half by a median rounded rib, with concave groove on either side. Beak short, 

 obliquely truncated by a rather large foramen, completed by a part of the umbo of the 

 opposite valve and by two small lateral deltidial plates. Surface of valves densely 

 covered with very fine radiating stria; of unequal width, and increasing in number through 

 bifurcation and the interpolation of shorter riblets. Colour dirty white, sometimes rayed 

 with broad pencils of black. Loop short and simple, incomplete when young, but with 

 age becoming annular through the union of the crural processes. Length 11 lines, by 

 9 in breadth and G in depth. 



Rub. L. E,eeve says " Mr. Cuming possesses two or three specimens, all exactly alike, 

 procured, he fancies, from the dredgings of Sir E. Belcher in the Strait of Corea." I have 

 seen and possess a number of specimens of tliis shell, which Mr. Sowerby assures me were 

 obtained near the Cape of Good Hope, its probable habitat. 



Ohs. ]\tr. Lovell Reeve considers this to be a good and well-marked species, and in 

 this statement I feel disposed to concur. I have seen a great many specimens of the 

 shell, some as wide as long, others longer than wide, and all presenting a more or less 

 well-marked biplication. In some exceptional examples there existed also an additional 

 rib on the lateral portions of the dorsal valve. T. radiata is remarkable, as observed by 

 Mr. E-eeve, on account of being very often sparingly rayed with black. It is a smaller 

 shell than T. cancellata, its nearest ally. In some specimens the foramen becomes 

 complete by the union of the deltidial plates, but this appears to be the exception and 

 not the rule. 



18. Terebkatulixa cancellata, Koch, sp. (Plate VI. figs. 1-8.) 



Terebratula cancellata, Koch, in Kiister, Concli.-Cab. vol. vii. p. 35, pi. 24. figs. 11-13, 181-3. 

 Terebratula, species quajdam ignota, Menke, Moll. Nov. Holland, specim. p. 35, no. 192. 

 Terebratula cancellata, So-nerby, Tlies. Concliyl. p. 358, pi. Ixxi. figs. 93-95, 1846. 

 Terebratula [Terebratulina) cancellata, Reeve, Conch. Icon. pi. iv. fig. 13, 18G0. 



Terebratulina cancellata, Dall, Proc. Acad. Nat. Sci. Philadelphia, p. 179, 1873; Davidson, Report on 

 the Brachiopoda, Voyage of H.M.S. 'Challenger,' Zool. vol. i. p. 37, pi. i. figs. 11-16, 1880. 



Shell rather large, elongated oval, livid brown or light yellowish with darker concentric 

 bands, widest about the middle, nearly straight in front. Dorsal valve very convex, 

 flattened longitudinally along the middle, from which the lateral portions slope away at 

 a strong angle. Ventral valve convex, rather less deep than the opposite one and some- 

 times flattened towards the front ; l)eak incurved, tapering, moderately produced and 

 truncated by a rather large foramen, which is very slightly separated from the hinge-line 

 by a very narrow deltidium, the beak often slightly overlying the um])o of the dorsal 

 valve. Surface of both valves ornamented with a great number of delicate raised striic 

 or riblets, increasing in number at various distances from the beaks by the interpolations 

 of shorter riblets. The surface is also crossed at intervals by fine concentric lines of 



