86 LUCINID^E. 



was met with, close in shore, at Littleham Cove. Though im- 

 mediately put into water no organ was exserted, except at the 

 centre of the ventral range a small portion of a pointed foot. 

 As the animal continued apathetic it was opened, when a 

 large corrugated subcylindrical foot became visible, which on 

 being divided proved to be tubular, but near the body it 

 appeared slightly geniculated. On each side there was one 

 rather elongated branchial plate, apparently divided by the 

 branchial artery in two portions ; these were connected and 

 doubled on each other, forming one thick plate, of a darkish 

 brown colour, shot with a hue of pink, very closely and 

 strongly decussated by the branchial vessels. No palpi were 

 seen. The liver is brownish-green. The margins of the shell 

 are plain, and the edges of the mantle loosely sinuated. The 

 posterior adductor scar is pyriform, the anterior one narrow 

 and strap-shaped. Of the two primary teeth in each valve, 

 one of each is cloven ; there is also an anterior lateral one in 

 both valves. 



Another specimen has this year (1853) occurred, of the 

 same size, and at the same habitat. It proved lively, and 

 has enabled me to offer some additions and explanation. The 

 foot is very narrow but lancet-pointed, and when fully ex- 

 tended is nearly as long as the vertical measure of the shell ; 

 it is always in the first instance exserted from the ventral 

 central point, and from thence can move itself anteally to a 

 right angle. It is transversely and longitudinally wrinkled, 

 and when alive has the aspect of being roughly shagreened ; 

 when dead it appears intensely corrugated across and length- 

 ways ; it has a decided heel near the junction with the body, 

 and is beyond doubt tubular to within a short distance of the 

 termination, and possibly may be entirely perforated. I made 

 with the scissors two sections before the tubular structure was 

 visible, but in so delicate an organ the pressure of the knife 

 might close a real perforation, which I believe exists ; not to 

 admit water either to the branchiae or viscera, as some natu- 

 ralists think, but to render the foot a potent locomotive organ 

 by inflation, and having the power of opening and constricting 

 the perforation for the issue and admission of the water. The 



