DE. T. DAVIDSON ON EECENT BEACHIOPODA. 55 



Waldheimia Grayi, A. Adams, Anu. & Mag. Nat. Hist. 3rd ser. vol. xi. p. {)[), 18G3 ; Davidson, Proc. 

 Zool. See. p. 30I-, pi. xxxi. figs. 7 & 8, 1871 ; Dall, Am. Journ. of Concli. vol. vi. p. 110, 1870, ami 

 Proc. Acad. Sci. Philadelphia, 1873, p. 182; G. Duiiker, Index Moll. Maris Japonici, p. 252, 1882. 



Shell variable in shape, squarely subpentagoual or subtriaugularly semicircular, 

 longer or broader than ^vide. Iliug-e-line either nearly straight or very obtusely angular, 

 shorter or longer than the breadth of the shell ; lateral margins rounded, nearly straight 

 or gently curved in front. Dorsal valve very moderately convex, somewhat flattened 

 and more or less longitudinally depressed along the middle. Ventral valve very much 

 deeper and more convex than the dorsal one ; beak short, bent backwards, nearly straight 

 or very Little incurved, and obtusely truncated by a large, transversely oval, incomplete 

 foramen, always more or less eroded, margined anteriorly liy the dorsal valve and by two 

 small labial rudimentary deltidial plates ; beak-ridges strongly marked, leaving between 

 them on the hinge-line a wide triangular almost flat area. Surface of valves marked by 

 a number of strong bifurcating radiating angular costse, of which the central one is 

 usually the largest. Valves traversed by numerous more or less prominent scale-like 

 zigzag concentric lines or ridges of growth. Shell-structure punctate. Colour 

 yellowish, with concentric bands of crimson colour, deeper in tint at or near the 

 projecting concentric ridges of growth. Proportions very variable. Two large examples 

 measured : — 



Length 1 inch 4 lines, breadth 1 inch 3 lines, depth 10 lines. 

 1 '^ 17 9 



') -■- 3) — J5 )) -■- 5) ' >5 55 ^ 55 



In the interior of the dorsal valve the cardinal process is wdde and narrow, the hinge- 

 plate large, mesial septum strong, extending to abovit half the length of the valve. Loop 

 long and simple ; the principal stems attached to the base of the hinge-plate extend to 

 about four fifths of the length of the valve before becoming reflected. 



Sab. Hakodadi, Mososeki, Japan, in 7 fathoms (Adams). Strait of Corea (Belcher 

 and St. John), in 37 fathoms. Dall mentions also Catalina and Monterey. 



Obs. This very remarkable and beautifvil shell is, as already stated, very variable in 

 shape, so much so, indeed, that some malacologists have felt disposed to divide it into 

 two species ; and, as observed by Dall, it is sometimes hardly possil)le to distinguish it 

 exteriorly from some specimens of Terebratula transversa, Sow., var. caurina, Gould, 

 or T. occidentalis, Dall, except by the loop, which in W. Grayi is simple, while in the 

 others it is three times attached, as in Terebratella. 



Prior to 1852, the shells of the species under description had erroneously been referred 

 to the Terebratula {Krausslna) rubra of Pallas, to which they also bear some external 

 resemblance ; and it was only after careful examination of the interior calcareous support 

 of the labial appendages that I discovered that they belonged to two very distinct 

 genera. As observed by Lovell Eeeve, m his ' Monograph of Terebratula,' the foramen of 

 the shell naturally becomes more or less eroded and enlarged according to the roughness 

 with which the creature is liufTetcd about in the place of its attachment, owing to the 

 shortness of its peduncle. He also observes that the deltidial plates meet in tlie middle 

 in very young examples, and that the ribs of W. Grayi are not really scaled, but scales 



