2<S TONICIA. 



>usly pencilled and marked with olivaceous; beaks small, con- 

 spicuous. Jugal area very small, smooth in front. Central areas 

 with :ilout 20 smooth riblets, curving toward the middle on the 

 median part of the areas, and toward the outside of the areas radiat- 

 ing outward. Lateral areas scarcely raised, having faint rows of 

 granules; at diagonal rib and at sutures having slight elongated 

 granules toward the sutural ribs and rows of metallic dots next the 

 diagonal ribs. Anterior valves with granules and irregular rows of 

 metallic dots alternating; crenate at suture. Posterior valve with 

 median, raised, swollen mucro ; posterior slope straight. Length 28, 

 breadth 18 mill. 



The single specimen collected by Coppinger is thus described by 

 Smith : It is of a greyish-pink color, copiously blotched with black 

 along the sides of some of the valves. The headplate * -::- 

 insertion edge is much thickened, coarsely striated externally, and 

 is divided by 8 short narrow slits. The exterior surface is coarsely 

 subsquamately granulated throughout, and exhibits numerous black 

 raised dots, disposed in rather irregular radiating series. The 

 second valve is long in comparison with those which follow, feebly 

 peaked behind ; the fourth, fifth and sixth plates are about equal in 

 size and a trifle broader than the third and seventh. All the inter- 

 mediate valves are very coarsely ridged and sulcated on the central 

 areas, and coarsely grained and minutely black-dotted on the sides 

 (lateral areas). The ridges are flat-topped, clean-cut, nearly smooth, 

 attenuated posteriorly, wavy, converge on each side toward the front, 

 and the intervening grooves are feebly punctate. All have the 

 hinder margin nearly straight and but feebly pointed at the poste- 

 rior apex. * * * The posterior valve is strong and thick, obtusely 

 mucronated in the center, very coarsely striated and serrated upon 

 the thickened insertion-margin, which is subdivided by about 10 dis- 

 tinct notches. The interior of the valve is liirht livid bluish, with a 

 reddish stain along the middle of all, with the exception of the last. 

 The mantle, as described by Reeve, is simply "horny." Length, 

 without girdle, 18, diam., of fifth valve 9 mill. Reeve's type is a 

 larger >peeimen. lieinir -4 mill, long, 13 wide, without girdle. 



I - \i:ri.vn:i:i Aiiiras. IM. 40, ficr. 7. 



Shell ovate, elevately convex. carinat< d. :i>hy white, ornamented 

 at the hinder edges of the valves with pale spots, the spaces between 

 which are very dark olive, melting into einfu>rd hands of a paler 

 hue which extend nearly across the valves; valves rostrate, undul- 



