122 WORMS. 



gile, gaping at one end, fixed by a beard of silky fila- 

 ments: hinge without teeth, the valves connected on 

 one side iiearJy the whole length. 



C. With a single valve, and more or less spiral. 



50. NAUTILUS. Inhabitant obscure, shell divided info 

 several compartments or cells communicating with 

 each other by a small aperture. 



51. CYPRJEA. Inhabitant, a Limax : shell involute, ra- 

 ther ovate, smooth, obtuse at each end: aperture 

 linear, extending the whole length of the shell, and 

 toothed on both sides. 



52. BULLA Inhabitant -d\\\M\ to a Limax: shell convolute, 

 without teeth : aperture more or less contracted, lon- 

 gitudinal, oblong, entire at the base : pillar oblique, 

 smooth. 



33. VOLUTA. Inhabitant a Limax : shell spiral: aperture 

 longitudinal, reaching nearly the whole length of the 

 shell, without beak : pillar twisted or plaited, without 

 perforation or interior lip. 



54. Bucci>iUM. Inhabitant a Limax: shell spiral, gib- 

 bous : aperture ovate, ending in a short canal leaning 

 to the right, with a retuse beak or projection. 



55. STROMBUS. Inhabitant a Limax : shell spiral: aper- 

 ture much dilated, the lip expanding and produced 

 into a canal leaning to the left. 



56. MUREX. Inhabitant a Limax: shell spiral, mostly 

 rough with membranaccous folds or knobs : aperture, 

 oval, ending in a straight entire canal, sometimes 

 slightly reflected. 



57. Tuocnus. Inhabitant a Limax: shell spiral, more 

 or less conic : aperture somewhat angular or rounded, 

 transversely contracted : pillar placed obliquely. 



58. TURBO. Inhabitant a Limax: shell spiral, solid: 

 aperture contracted, orbicular, entire. 



59. HELIX. Inhabitant a Limax : shell spiral, more or 

 less transparent, brittle . aperture contracted, round- 

 ish-oval, or semi lunar. 



60. NERITA. Inhabitant a Limax : shell spiral, gibbous, 

 llattish beneath : aperture semiorbicular : pillar-lip 

 transverse, flattish and truncate. 



61. HALIOTIS. Inhabitant a Limax : shell dilated, ear- 

 shaped, with a longitudinal row of orifices along the 

 disk : spire lateral, flat upon the shell. 



D. With a single valve, and idthout spire. 



C2. PATELLA. Inhabitant a Limax : shell more or less 

 conic, shaped like a bason, mostly without spire. 



63. DENTALIUM. Inhabitant a Terebella : shell tubular, 

 detached, -straight or slightly curved, not divided into 

 chambers, pervious, and open at both ends. 



