50 corbulid^e. 



curved ; rostral prolongation considerable, much more attenu- 

 ated than in the other species : beaks small and mammillary ; 

 unibones by no means prominent ; dorsal area narrowly exca- 

 vated on the posterior side : cartilage orangecolour, contained 

 in a triangular receptacle which shelves outwards : hinge-line 

 straight : hinge-plate narrow and slight : teeth, an extremely 

 minute tubercular cardinal in the left valve, and a strong 

 erect and triangular lateral in the right valve on the posterior 

 side : inside glossy, with a rib on the posterior side : muscular 

 scars well marked ; anterior irregularly oblong, posterior tri- 

 angular. L. 0-25. B. 0-415. 



Var. lactea. Shell milk-white, more glossy, transparent, 

 and delicate, having only two ribs on the posterior angle, 

 besides those on the rostral process. 



Habitat : Loch Fyne, 40-70 f., with the last species 

 (M f Andrew and Barlee) ; Cumbrae, Firth of Clyde 

 (Robertson) ; Skye and Shetland (Barlee and J. G. J.) . 

 The variety was dredged by me on a sandy bottom, in 

 78 f., from 40 to 50 miles east of the Whalsey Skerries, 

 Shetland. Upper tertiaries of Greece (Deshayes) ; 

 Antwerp (Nyst) ; Guise-Lainotte, France (De Koninck) ; 

 Calabria (Philippi). It inhabits the coasts of Scandi- 

 navia at depths ranging between 10 and 100 f. (Loven 

 and others) ; Carthagena, in 30 f., and Gibraltar, in 45 f. 

 (M ( Andrew) ; Provence, in 60 f. (Martin) ; Gulf of 

 Genoa, in 25 f. (J. G. J.) ; Adriatic (Chiereghini) ; 

 Naples (v. Martens) ; iEgean, in 20-185 f. (Forbes) ; 

 Malta, in 40 f., Gulf of Tunis, in 35 f., Madeira, in 

 18-24 f., and Teneriffe, in 20-35 f. (M'Andrew). 

 Specimens dredged by the late Professor Barrett in 

 deep water at Jamaica are scarcely distinguishable from 

 those of the North Atlantic. 



This exquisite shell cannot well be mistaken for 

 N. abhreviata ; their shape, sculpture, and dentition are 

 very different. 



Nvst seems to have been the earliest describer of it, 



