TRIBE PHOLADARIA. 



TRIBE PHOLADARIA. 



Devoid of a tuhxilar sheath : valves with accessory pieces or 

 consider ah Ii/ tjajnng posteriorly . 



PHOLAS. 



Shell bivalve, equivalve, transverse, gaping at both extremities, with 

 various accessory pieces either on. the hinge or below it ; inferior 

 margin of the valves irifiected. 



* Valves not divided by a radiating groove. 



P.Dactylus.* Zm. 1110.— Z>.p. 35.— Ch.f. 859.~^.f. 168. 

 /. 2,3,4.— Lam. I.— Don. t. 118.— i?. t. \'.f.7.~Sow. G.— 

 Reeve, t. 24./. \.— Wood. G. C. t. \3.— Turt. B. p. S.~3Iont. 

 p. 20. — W. t. 2. ,/". 1. Elongated-oblong, beaked at one end and 

 rounded at the other, with concentric waved muricated ridges and 

 indistinct radiating striae towards the beaks ; margin above the 

 umbones reflected, circular and supported by numerous small plates 

 so as to form quadrangular cells : 4 accessory plates. 4 or 5. 

 — Europe.^ 



P. Orientalis. Gmel.32\Q.—D. p.36.—La7n.2.— Ch.f. 

 860 — W. t. 2.f. 2. Elongated-oblong, white, brittle, and nearly 

 closed at one end, one half of each valve smooth and the other 

 marked with reticulated striae ; margin straight. 1^ . . 6. — Siamand 

 Tranquehar. Someivhat resembles the last but is not heahed. 



P. Candida.* Lin. 1 1 1 \.—D. p. 36.— Lam. 3.— TF. /. 2. /. 3. 

 Don. t.\32. — Ch.j:H6l, 2.— Wood. G. C.t. \4.f.3, 4. Oblong, 

 rounded at both ends, ventral margin entirely convex and not at all 

 indented, covered with decussated prickly strise which posteriorly 

 form distant radiating rows of prickles (but not ribs) : margin above 

 the hinge reflected and covered with an elongated accessorial plate : 

 a toothlike process on the hinge, ascending obliquely and anteriorly, 

 f . . 2. — Europe. 



P. Parva.* Mont. p. 22. t. 1 ./. 7, 8.—D. p. 38.— IF. f. 2.f. 6. 

 — Turt. Biv. p. 9. — P. Dactyloides, Lam, 4 . Ovate, beaked poste- 

 riorly, rough with reticulated rather prickly striae except anteriorly ; 



2 P. Oblongata Say is probably this species, although its beak 

 and the number of its accessory valves is not mentioned. 



P. Callosa. Lam. 8. Ovate-oblong, sinuatcd, posteriorly with 

 curling striae, anteriorly smooth ; hinge plate rather prominent and 

 globose. — Bayonne. From the brevity of this description, lam 

 unable to recognize the species, the figures quoted by Deshoiifn 

 however (List. t. 433. and Broohe, t. 1 . /'. 7, 'S.) ore distorted 

 Daclyli. 



