TKITON. MOLLUSCA. 37 



lique, subfoliaceous. 1^ inch long. Inhabits the European seas. 

 Penn. Brit. Zool. iii. pi. 78. 



This species, one of the most common of the genus, is found plentifully in the 

 Frith of Forth of all ages. The young want the dilated lip, and as the animal grows 

 older this lip increases in size till it acquires its perfect form. In some old shells it 

 is of extreme thickness. 



FAMILY V. CANALIFERA. 



Shell with a canal more or less long at the base of the aperture, 

 and of which the right margin does not change its form as 

 the animal advances in age. 



1. With a permanent varix on the right lip, and varices on 



the spire. 



Gen. 26. TRITON, Lam. Mureoc, Lin. 

 Shell oval or oblong, canaliculated at the base, with the varices 

 either alternate or nearly solitary, and never forming longi- 

 tudinal rows ; aperture oblong, with one operculum. 



T. variegatum, Lam. (M. Tritonis, Lin.) Shell elongate conical, 

 trumpet-shaped, ventricose, and the whorls crenulated at the su- 

 tures ; inner lip grooved,, and the lip short ; colour whitish, ele- 

 gantly variegated with reddish brown spots. 12 to 16 inches 

 long. Inhabits Indian and American seas. Bonan. 3. fig. 188. 



T. Australe, Lam. Shell ovate-conical, trumpet-shaped, ventricose 

 below, transversely bordered and striated ; longitudinal striae fine- 

 ly decussated ; clouded with white and rose-colour, and marked 

 with reddish ; the whorls of the back with two rows of tubercles ; 

 columella with one fold above, smooth in the middle, and rugous 

 at the base. 6J inches long. New Holland. Lam. vii. 179. 

 Several extinct species of this genus have been found in Britain, chiefly in the 



London clay. 



Gen. 27. MUREX, Lin, Lam. 



Shell oval or oblong, canaliculated at the base, with rough spi- 

 nous or tubercular varices ; aperture rounded or oval ; three 

 or more varices in each turn of the spire, the lower ones unit- 

 ing obliquely with the upper into longitudinal rows ; opercu- 

 lum corneous. 



The shells of this genus are at once distinguished from their having at least three 

 rows of varices or ridges on each whorl. Many of them display beautiful colouring, 

 and some are of considerable size. 



M. cornutus, Lin. Shell roundish, transversely striated, with se- 

 ven varices, and subulate oblique spines ; beak long, subulate, 

 and irregularly spinous ; brownish white. 6 inches long, of which 

 the beak forms the half. Indian seas. Lister, pi. 901, fig. 21. 



M. haustellum, Lin. Shell subovate, with three thick varices and 

 intermediate smaller ribs ; beak long, slender ; spire short ; co- 

 lour fulvous red, transversely marked with blackish brown, and 

 the inner margin of the aperture rose-coloured. 4 inches long, 



