128 INVERTEBRATA OF MASSACHUSETTS. 



Modi" OLA nexa. 



Shell ovate, ferruginous, beaks prominent, and placed considera- 

 bly behind the anterior extremity ; minutely reticulated with fine, 

 corrugated, concentric, and radiating lines. 



Figure 86. 

 State Coll., No. 154. 



Shell small, thin, long-ovate, largest behind, slightly produced 

 at the posterior extremity ; basal edge less curved than the su- 

 perior edge, which is moderately compressed ; beaks prominent, 

 pointed, directed forwards, scarcely touching each other, placed 

 unusually far from the anterior extremity ; a rather sharp ridge 

 passes from the beaks diagonally across the shell, but loses itself 

 about half way across. Surface very beautifully sculptured with 

 a net-work of very minute, crowded lines of growth, and very 

 numerous, fine, indented radiating hues or ridges, which are obso- 

 lete along two thirds of the base, and most conspicuous behind, 

 where a very fine hne divides into two each ridge, going to the 

 extreme posterior portion ; while above these, on the compressed 

 portion, a beautiful lace-work of hexagonal indentations is formed. 

 The portion in front of the beaks is conspicuously radiated. 

 Epidermis a rusty-brown, with shades of olive, glossy ; interior 

 livid, with a pearly or silvery lustre, and with minute, radiating 

 lines ; cavity of the beaks large ; margin simple. Length tV 

 inch, height -^^ inch, breadth ^ir inch. 



This new and beautiful shell was taken by dredging in the har- 

 bour of Provincetown, by Colonel Totten, where he obtained 

 several living specimens. 



It is allied to M. discors and M. discrepans by its outline, and by 

 the triangular poriion across the disk nearly destitute of radiating 

 lines. But it is more compressed than either of those shells, less in- 

 equilateral, and its sculpture far more beautiful. The radiating lines 

 seem all to have indentations or punctures like the wing-covers of 

 many large beetles (Cdrahi). The honey-comb arrangement near the 

 hinge margin is very beautiful. Dr. Loven has sent me the shell, 

 from Sweden, as the true M. discrepans of Montagu and Turton ; but 

 in this he is at variance with the opinions and figures of all other authors. 



