SOLEN. 251 



posterior area, usually assumes a chesnut or rusty cast 

 towards the ventral margin and the anterior side. 



The valves seem slightly more convex, and the extreme 

 difference of size between adult individuals of the usual 

 dimensions belonging to the two species is so marked as 

 almost to merit being regarded as characteristic. There 

 is, however, a variety, a scarce one though, whose ampli- 

 tude is on a par with that of siliqua ; but in general the 

 valves do not attain four inches in length, nor exceed half 

 an inch in width. 



Turton is in error when he declares the solitary tooth of 

 the right valve to be simple ; it is distinctly, but most de- 

 licately, grooved at its rounded apex. 



The animal of Solen ensis has been examined and figured 

 by M. Deshayes. It is very closely allied, as might be 

 expected, to that of siliqua. The siphons are very short, 

 the branchial one having a fringe of tentacula, irregular, 

 but simple, around its orifice, and a second circle of similar 

 organs just below. The anal has the second series only 

 develo2)ed, but its margins are slightly scalloped. Both 

 tubes are white below the second circle of cirrhi, but above 

 it they are minutely speckled with brown. The foot is of 

 a dull flesh-colour at the sides, its end paler, and obliquely 

 truncated. 



It is an inhabitant of rather deeper water than the last 

 species, ranging from five to fifteen fathoms, the ground 

 sand or shelly sand. 



Equally with siliqua, this species is at once both nu- 

 merous in individuals, and most widely diffused. It is 

 abundant at Scarborough and the North (Bean and Alder); 

 occurs at intervals along the eastern coast, from thence 

 to Devonshire (S. H.); and is common on sandy shores 

 from the south of England to Shetland (M 'Andrew). " It 



