241 



CHAPTER XIIL* 



PALiEOZOIC MOLLUSCA. 



Sanguinolites decipiens (M'Coy). 



Desc. Elongate-oblong, dorsal and ventral margins subparallel ; 

 beak incurved, small, depressed, about one-fifth the length 

 from the anterior end ; hinge-line long, not elevated (the in- 

 flected edges forming a nearly horizontal posterior lunette ex- 

 tending its entire length) j cardinal angle about 115°; anterior 

 end rounded, narrowed by an elongate, elliptic lunette; a strong 

 sigmoidally contorted diagonal ridge extends from the beak 

 to the respiratory angle ; posterior slope steeply inclined ; 

 posterior end slightly oblique, subtruncate, rounded ; ventral 

 margin with a wide, rather deep sinus in the middle, from 

 which a wide concavity extends nearly to the beak, and from 

 the diagonal ridge to the anterior end, which is convex an- 

 terior to the beaks ; surface marked with sharp concentric 

 wrinkles from the anterior lunette to the diagonal ridge. 

 Length 8 lines ; in proportion to the length, greatest width 

 (from beak to opposite margin) -^-^q; length of anterior end f-^^j 

 from the beak to end of hinge-line -^^q ; greatest depth of one 

 valve (about middle of diagonal ridge) j%^q. 



I have seen numerous specimens of this species from the Upper 

 Ludlow rocks, usually confounded with the so-called Cypricardia 

 cymbiformis (Sow.), which it strongly resembles at first sight, 

 although the anterior end is considerably longer. That fossil, 

 however, has simple erect dorsal margins, and belongs to the 

 genus Orthonotus, while the distinctly inflected dorsal edges 

 forming the elongate, concave, posterior lunette show the pre- 

 sent species to belong to the genus Sanguinolites. 



Not uncommon in the Upper Ludlow rock of Benson Knot, 

 Kendal, Westmoreland ; and in the micaceous grits of Llechc- 

 lawdd Myddfai, near Llandovery, S. Wales ; greenish schists of 

 Balmae shore, Kirkcudbright. 



[Col. University of Cambridge.) 



* The. species in this chapter date from the 'Annals ' for Sept. 1852. 



Q 



