UNIVALVES. — NAUTILUS. 79 



of the Nautili; but by far the greater number are found on 

 the British, and most of the European coasts. 



NAUTILUS— ^a«7or. 



Division I. — Spiral, with contiguous whirls. 

 Pompilius — Great-chambered. Scrobiculatus — Sunken-spire. 

 *Lacustris — Lake. 



Minute or Microscopic Shells. 



Calcar — Spur. Balthicus — Baltic. 



*Rotatus — Wheel, *Crassulus — Strong. 



*Lsevigatulus — Smooth. *Umbilicatulus — Umbilicated. 



*Depressulus — Compressed. *Lobatulus — Lobed. 



*Crispus — Keel-edged. Rugosus — Rtigged. 



*Beccarii — Beccaria's. Umbilicatus — Obliqice-jointed. 



Division II. — Spiral, with detached ichirls. 

 Spirula — Ram's-horv. 



Minute Shells. 

 Spengleri — Spengler's. Unguiculatus — Nail-shop' d. 



Division III. — Elongated and almost straight. 

 Minute. 

 *Semilituus — Half-crozier. *Spinulosus — Spinous-jointed. 



Lituiis — Crozier. *Sub-arcuatus — Sub-arcuated. 



*Carinatulus — Keeled. *Bicarinatus — Bicarinated, 



♦Obliquus — Obliquely-striated. Fascia — Banded. 

 Raphanistrum — Twelve-striated. Inaequalis — Unequal. 

 Raphanus — Seventeen-striated. Siphimculus — Piped. 

 *Costatus — Ribbed. *Legumen — Pod. 



Granum — Eight- striated. *Linearis — Linear. 



*Radicula — Bulbous-jointed. *Rectus — Straight. 



