112 JOURNAL OF THE NEW JERSEY 



by two extra valves, one placed in front of the other ; the hinge 

 plate broadly reflected over the umbones and a long, free, rib- 

 like projection under them ; pallial sinus reaching the centre of 

 the shell. Animal with a large, truncated foot, filling the pedal 

 opening ; combined si}»hons large, cylindrical, with fringed open- 

 ings. 



1. Pholas (Barneci) costata, L. (Figs. 16, 17). Shell large, 

 oblong-ovate, anterior end broader, covered with about 30 radi- 

 ating, toothed ribs; extra hinge pieces cartilaginous. L. 150; 

 H. 50 ; W. 50 ; U. J from anterior end. Animal straw-colored, 

 the tip of the siphons beautifully stippled with mahogany- 

 brown ; it burrows several feet deep, and so is difficult to obtain 

 alive. Dead and separated valves are frequently found. — Mass. 

 and south. 



2. Pholas (Barned) truncata^ Say. Shell oblong or somewhat 

 five sided, the anterior end being triangular and sharp pointed, 

 the posterior broadly truncate ; the surflice covered with coarse 

 lines of growth, and the anterior two thirds with rough, radiat- 

 ing riblets formed of toothed projections; extra hinge pieces 

 shelly. L. 75 ; H. 35 ; M. 30 ; U. J. Animal dark, smoky color. 

 Mass. and south. 



2. ZiRPH.EA, Leach. 



Shell oval, cardinal margin slightly reflected ; no extra valves, 

 but a membrane in their place. 



1. Zirphsea cris2KUa, L. Shell quite thick and strong, oval- 

 oblong, rounded behind, somewhat triangular but not acutely 

 pointed in front, gaping widely in front ; surface nearly equally 

 divided by a broad furrow extending from umbo to base, the 

 front portion covered with rough, radiating ribs ; hinge margin 

 only slightly reflected, and a protecting membrane instead of 

 extra valves. L. 60 ; H. 35 ; W. 34 ; U. nearly |. • Frequently 

 larger, sometimes over 100 long. — Whole coast. 



3. Martesia, Leach. 



Valves lengthened behind, when full grown, by a plain border ; 

 umbonal valves one or two ; surface wdth one or more furrows. 



1. Martesia ameiformis, Ssij . Shell somewhat wedge-shaped; 

 posterior end about J the width of the anterior end and rounded ; 

 anterior end somewhat truncated; a deep furrow extends across 



