122 WORMS. 



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

 ments: hinge without teeth, the valves connected on 

 one side nearly the whole length. 



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



50. Nautilus. Inhabitant obscure, shell divided into 

 several compartments or cells communicating with 

 each other by a small aperture. 



51. Cypr^a. Inhabitant, a Limax : shell involute, ra- 

 ther ovate, smooth, obtuse at eaeh end: aperture 

 linear, extending the whole length of the shell, and 

 toothed on both sides. 



52. Bulla Inhabitant allied to a Limax: shell convolute, 

 -without teeth : aperture more or less contracted, lon- 

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

 smooth. 



53. 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. Buccinum. 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 membranaceous folds or knobs : aperture 

 oval, ending in a straight entire canal, sometimes 

 slightly reflected. 



57. Trochus. 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 semilunar. 



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

 flattish beneath : aperture semiorbicular : pillar-lip 

 transverse, flattish and truncate. 



61. Haliotis. Inhabitant a Limax : sliell dilated, ear- 

 shaped, with a longitudinal row of orifices along the 

 disk : spire lateral, flat upon the shell. 



D. With a single valve, and without spire, 



62. 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. 



