CORBULID^. 41 



not so inequivalve as that of Corhula ; it is oblong, 

 and rather square at both ends. When the valves are 

 seen without the green epidermis which covers thenij 

 they look very much like those of a Saxicava. The 

 only species is S. Binghami. 



III. NetERA. — All the species of this beautiful genus are 

 elegantly formed, presenting the graceful curved lines 

 of the pear or fig ; the tubes are short and divided, and 

 surrounded at the sides by long cirrhi, or threads, end- 

 ing beyond the orifices by little divided paddles ; the 

 foot is curved and pointed ; the shell is pyriform, and 

 has a spoon-shaped pit for the internal part of the li- 

 gament. The British species are — 



N. cuspidata : shell smooth, delicately brown outside, pink- 

 ish inside, about three-quarters of an inch long, very 

 bulky in front, and with an elegantly curved beak at 

 the back : found in deep water far from land, at Cape 

 Clear, Firth of Eorth, Northumberland, Zetland, etc. 



N. ahhreviata : very small ; the beak or rostrum short, with 

 a rib before it : in deep water at Loch Fyne. 



iV". costellata : small, more decidedly rostrated, with two or 

 three ribs radiating from the umbo between the ros- 

 trum and the swelled part of the shell : dredged by 



