PHASIANELLA. 321 



mass consists of the usual palate, and a long tongue, sup- 

 ported by corneous green plates. In the males, on the right 

 side, is a small, green, suboval verge ? The ovarium is of a 

 blue milk colour, entwined with the liver, and fall of ova in 

 July. The branchial apparatus is situate as in all the Littorirue, 

 and consists of a single pale green arcuated plume, having 

 at the anterior end numerous close-set transverse vessels, 

 which are long at their commencement and taper gradually 

 to near the pericardium. M. Cuvier states that in his Pha- 

 sianella he found two plumes ; I think our only species has 

 but one. 



The foot is not trochidan, except the upper lobe ; the sole 

 is a perfect elongated oval, as in Littorina. The locomotive 

 functions are curious. When the animal marches, one half 

 of the longitudinal area, bounded by a central incised line, 

 is first extended and fixed ; the other half is then brought up 

 and in like manner fixed, whilst the first half makes a pro- 

 gression, and so on; thus half the foot is alternately in 

 motion, giving the animal a lateral oscillatory progress. This 

 kind of march is confined, I believe, to this species, and to 

 most, if not all, of the true Littorina that have the longi- 

 tudinal scission or depressed line of the sole more or less de- 

 veloped. The sole is edged with a light lead-coloured line, 

 and the upper surface is laterally brindled with semicircular 

 broken pink lines. The upper coriaceous brown lobe at its 

 posterior end supports a shield-like paucispiral operculum, 

 testaceous, and convex externally ; it then coasts each side of 

 the foot, having, as in Trochus, 24 lateral, long, setose, 

 white, sometimes pale red-brown, or pale green vibracula, 

 varying in size, the middle ones being usually the smallest, 

 and finally forms on each side the head a scalloped green, or 

 pale red neck-lappet, furnished with 6-9 plain dentations or 

 cirrhi, which are more developed on the columellar side ; the 

 upper lobe throughout is more or less speckled with red and 

 brown streaks. 



This animal, in the beauty of its shell and splendid colora- 

 tion of the organs, is one of the most gorgeous of the British 

 Gasteropoda ; the only other animals that can be brought into 



