186 MANUAL OF THE MOLLUSCA. 



objects of superstitious dread, on account of their grotesque forms, and the 

 imaginary properties of their fluid, which was held to be poisonous and to 

 produce indelible stains.* 



Fossil: one or two shells of the newest tertiary in Sicily have been doubt- 

 fully referred to this genus. 



Sub-genus, Aclesia (dolabrifera) Rang. Shell trapeziform. Side-lobes 

 closely enveloping the body, lea\dng only a small dorsal respiratory opening, 

 surface ornamented with filaments. W. Indies. 



DoLABELLA, Lamarck. 



Type. D. Rumphii, PI. XIV. fig. 15. Etpn. Dolahella, a small hatchet. 



Shell hard, calcarious, trigonal, with a curved and callous apex. 



Animal Like Aplysia, with gill near posterior extremity of the body and 

 lateral crests closely appressed, leaving only a narrow opening ; ornamented 

 with branching filaments. 



Distr. 12 sp. Medit. Mauritius, Ceylon, Society Ids. Sandwich Ids. 



NoTAECHUS, Cuvier. 



Type. N". Cuvieri, Bl. Etym. Notos, the back, archos vent. 



Syn. Busiris (griseus) Risso, ? Bursatella (Leachii) Bl. 



Animal shell-less, ornamented with filaments, sometimes dendritic, foot 

 narrow, linear, lateral crests united, leaving only a narrow branchial slit ; 

 gills not covered by an opercular mantle lobe. 



Distr. 4 sp. Medit. Red Sea. 



Icarus, Forbes, 1843. 



Type. I. Gravesii, F. Syn. Lophocercus (Sieboldtii) Krohn, 1847. 



Shell likeBulleea; convoluted, thin, ovate, covered with epidermis, outer 

 lip separated at the suture, posterior angle inflected and rounded. 



Animal slender, papillose ; tentacles 2, ear-shaped ; eyes sessile on sides 

 of head; side-lobes reflected and partly covering the shell, united behind; 

 tail long and pointed. 



LoBiGEE, Krohn. 



Type, L. Philippii, PL XIV. fig. 16. SicUy. 



Shell oval, transparent, flexible,^" slightly convoluted ; covered with "^ 

 epidermis. 



Animal slender, papillose, with 2 flattened, oval tentacles, and minute 

 sessile eyes on the sides of the head ; shell exposed on the middle of the back, 

 covering the plume-like gill ; sides with two pairs of rounded, dilated lobes, 

 or natatory appendages, foot linear, tail long and slender. 



* Aplysia, (from a and pluo) un-washable ; the Aplysia of the Greek Fishermen 

 ^•ere sponges unfit for washing ! 



