106 



ARCA R. Mont. p. 55. t. 27. f. 7. Pen. 4.p. 217. 

 D. p. 245. Oval, anteriorly produced, curved and 

 rounded, glossy, pale horn color, with fine regular and 

 reflected concentric striae, which however become ir- 

 regular in crossing the very slight longitudinal anterior 

 ribs; central tooth obsolete, margin entire. i...f 

 Frith of Forth. 



N. MINUTA. Turt.B.p. 178. F. p. 402. ARCA. 

 M. Pen. l.jp. 216. Mont. p. 140. Lin. T. S.p. 92. 

 Dor. Cat. t. I./. 16. D. p. 245.Turt. D. p. 11. 

 /. 98. A. CAUDATA. Don. 3. t. 78. Oval, anteriorly 

 produced, curved and truncated, white or yellowish with 

 a few ridges crossing the transverse striae, margin entire* 

 !...!. Tenby, Sandwich, Scotland. 



ORDER. MONOMYARIA. 

 With one siphonal scar. 



TRIBE, MYTILACEA. 



Hinge with the ligament marginal, partly inclined f 

 linear, extending along a great part of the anterior 

 border. Rarely foliated and adherent. 



GENUS. MODIOLA. 

 Subtransverse, eqitivalve, regular, posteriorly very 



