196 auriculid^;. 



expanded edge by a callous rim, on which are seated from 

 three to six teeth (occasionally produced in ridges), which 

 vary as to size and solidity. Inner lip with an oblique 

 fold or pliciform tooth on the pillar, and with two central 

 (besides, oftentimes, one or two additional posterior den- 

 ticles) comparatively horizontal teeth, of which the lower 

 is sublamellar and decidedly the larger and more promi- 

 nent. No umbilicus, but the reflected pillar lip is not 

 always thoroughly appressed anteriorly. Length of a 

 large individual nearly the third of an inch ; breadth 

 almost two lines. 



The animal is yellowish or bluish-white, with conspicuous 

 and approximated eyes at the inner bases of its somewhat 

 compi*essed tentacles. 



This form always occurs in the neighbourhood of the 

 sea. It is found in many localities, especially on the 

 southern and western coasts of England. A variety 

 occurs in vast abundance in ditches at Cobo in Guern- 

 sey (F. D. Lukis) ; in South Wales (Jeffreys) ; Loch 

 Fyne (Jeffreys) : " in crevices of the cliff a little above 

 high water-mark at the south end of South Shields 

 sands, rare" (Hancock). In the north, east, and south of 

 Ireland (W. Thompson). 



The shell of ini/osotis is precisely similar, except in the 

 aperture, but for the most part stronger, and usually of a 

 deeper tint of colouring, being sometimes chocolate-brown, 

 and edged with white below the suture ; more frequently, 

 however, yellowish brown. Inner lip with only two or 

 three teeth, the denticles being always, and the posterior 

 tooth frequently, wanting ; callosity of the outer lip solid, 

 and either unarmed, or with only a single tubercular or 

 dentiform projection where the rim is abruptly attenuated 

 just below the site of the opposite posterior tooth. 



