TAPES. 357 



hinge or posterior side : paUial scar broad and polished, deeply 

 and widely sinuous at the posterior end : muscular scars trian- 

 gular, large, and also polished. L. 1*5. B. 1-7. 



Yar. 1. perforans. Shell more or less distorted, and either 

 longer, broader, or shorter than usual, or having the anterior 

 margin abruptly truncate. Venus perforans, Mont. Test. Brit, 

 p. 127, t. 3. f. 6. 



Var. 2. ovata. Shell more convex, longer, and contracted 

 at each end. 



Yar. 3. ollonga. Shell much broader, being more produced 

 at each end. 



Yar. 4. plagia. Shell more produced at the posterior side, 

 which bends upwards (as in Lutraria elliptica, var. oblonga), 

 the anterior margin having a corresponding curve and being 

 obliquely truncate. Venus plagia, Jeffr. in Ann. Nat. Hist. 

 vol. xix. p. 313. 



HABITAT : Equally common and diffused with T. vir- 

 gineus ; but it is usually littoral, living in muddy gravel 

 or sand, and is seldom found below 7 or 8 fathoms. It 

 occurs in the Clyde, Belfast, and Sussex tertiary beds. 

 The T. perovalis of Searles Wood from the Coralline 

 Crag scarcely differs from the present species. Var. 1. 

 In crevices of rocks, and in deserted holes of Pholades 

 and Saxicava arctica, generally attached by a byssus, 

 from Unst to Jersey. Var. 2. Exmouth (Clark) ; Cork 

 (Humphreys). This is analogous to the variety Sar- 

 niensis of the last species. Var. 3. Cork (Wright); 

 Bundoran, co. Donegal (J. G. J.); Shetland (Barlee). 

 Var. 4. Lerwick and Deal Voe (J. G. J.). T. pullastra 

 inhabits the coasts of Norway, South Sweden, and Den- 

 mark, and those of the north and west of France ; and 

 (as Venus yeographica, which I consider a variety of the 

 same species) it is spread over all the sea-bed lying be- 

 tween Gibraltar and the Morea. It is also one of the 

 Uddevalla fossils. 



According to Montagu these shells are called " pull- 



