buccal appendices very long, pointed, rigid, and applied 

 against each other like a kind of jaws; the posteriors 

 equally rigid, and vertical. 



NUCULA LIMATULA. 



SPECIFIC CHARACTER. 



Oblong-ovate, rostrated, pellucid ; beaks subcentral. not 

 elevated ; margin entire. 



DESCRIPTION. 



Shell transversely elongated subovate, green olive, near- 

 ly pellucid, smooth, polished, w^ith slight inductions of in- 

 crement: beaks not prominent above the curve of the 

 hinge margin; hinge margin anteriorly abruptly com- 

 pressed ; the compression not reaching the tip ; rectiline- 

 ar nearly to the tip v\ hich is a little recurved ; posteriorly 

 almost regularly, but obtusely arquated : posterior margin 

 regularly rounded : anterior margin somewhat rostrated, 

 not truncated : within a little perlaceous : margin entire : 

 liTie of the teeth slightly interrupted and a little angulated 

 at the fosset, extending more than two thirds of the length 

 of the shell, rectilinear before and behind : teeth promi- 

 nent, numerous, acute, much angulated at their bases and 

 longer than the breadth of their bases : fosset triangular, 

 short, rather small, and but little oblique. 



PLATE XII. 



